Leon would have overlooked it, the slimy coating that is in Abkool's dagger but there is no way he could just let it pass. It's something he forebid the Shokoys to use and trade to other races.
"Where did you got that fluid?" His eyes almost close to a squint and his glare is not getting any signs of lifting. Abkool is confused of his reaction but seeing that he is covering his nose, maybe it is making some effect on him like what that man had told him.  
As a proud warrior, he pounded his chest and the other mermen followed. Crow is left to accompany and protect Hee-sun which catching all the ridiculing eyes of the rest of the mermen they are poking her. 
Abkool stomped his feet and then proudly said, "It is like what that man had told me! It might sound of me not fairly fighting but no. This is what you called being prepared. Reassured that I wouldn't do any underhanded tricks like this one. You see, ninja's in dramas put poison in their needles right? This is like that one! Fuefue~ A toxin that will surely kill you human!!" He loudly laughs and hit his chest which the other mermen is copying. Their loud voices had made a frown in Leon's forehead and seeing this, Abkool thought that the toxin is getting its effect but in a blink, Leon went to his side and slash his blade that almost cut his neck if he didn't evaded it in time. Abkool thought that the attack is done but the follow up attack is unexpected. 
From below, Leon slide his feet which Abkool jumps in the air to avoid being tripped but the trajectory changes midway and his precious manhood had been hit. There is no emotion to describe the pain or how did Abkool manage to still stand to his feet and block the punch that Leon given him. 
"What the...hmmmp!" He couldn't continue what he wanted to tell because Leon's attack is not getting done. When it felt like the attack had already finished and slowed down, the next blow become sharp and heavy. Or when it was fast that made your blood rush, in a blink it will become slower like the opponent is getting tired of continuous blows. It has no pattern and instead of Leon as the one attacking to get tired, Abkool is the one panting and feeling the ache in his muscles. He could not understand and grab a container in his waist and poured it over his blade.  
Seeing this Leon's eyes glinted a dangerous light and he kicks the ground to shot a bullet to Abkool's face. 
"Crow! Cover Hee-sun's nose!" He yelled and Crow followed without question. The liquid is pouring over the blade and Leon is becoming faster than before. 
"How...why!" Abkool cried before kicking the ground too and avoided the bullet that aimed to him and he swiftly slice through the air, aiming for Leon's head but in an inch distance, Leon duck his head before he motion his blade sideways and attempting to hit his waist which had grazed a little after Abkool reacted late. A small portion of the liquid seep through the wound and then Leon started to catch his breath. Since the first attack, he didn't covered his nose anymore and he felt like his head is going to explode from the multitudes of ideas sprouting and coming to it. He even not yet done executing the first idea and he is already doing the next. He feels like he had gain another body that doing multi tasking but in reality he is doing it by himself which looks like a perfectly sync in the eyes of others. 
『Metathione had been dozed in the veins. It's continuously affecting the rational thinking of the host. Do you want to removed it?』 
Like what he had suspected, Leon is right that he had sniff this from somewhere and somewhat familiar. Who would have thought that the reason for them to lose their father is right here in his eyes and him being affected by it makes his blood boils instead. 
The reverie that he thought would never haunt him. The wrath that he thought that had already died down through the passage of time. 
In just one sniff, all came back to him in ten folds.  
There is a reason to every actions and reading it from his father's will, he is even more furious. Remembering the past makes his aura he had accumulated over the millenium years that he is alive were pouring out of his body in an instant.  
Abkool is stunned to his place. Not only him but even the other mermen couldn't move from their place. They felt like they had bump into a huge strong wall and no matter what struggle they would do, they will not get passed it unless they have something to sacrifice and take risk.   
But no matter what struggle they would do or to sacrifice something valuable, the wall will stand as mighty with no weaknesses. 
That's how they picture Leon and what Leon see in his head are far more worse.  
He could see the image of his father, drooling and out of his control. He looks like someone that had attracted rabies and the way he behaves were similar from the actions he had when he was alive. Violence is only his brain dictates. His bloodshot eyes that had been his greeting to them everyday. Leon know very well that it was an illusion by the drug but seeing again the first man he wanted to kill with his own hands greatly infuriates him.
Leon doesn't care about the system anymore or it will get exposed. 
He doesn't care of his actions or what the outcome of this sudden show of dominance. 
He is not thinking of what comes after but just to quench the desire to kill and end the life of his father. The one that had brought him into this world. The reason that he is breathing and also the reason why he could no longer hold his mother within embrace in a very young age.  
The blade grew longer. The fuel that is making it run already depleted and now his energy is the one that is making it capable to do more than before. After being exposed to the System N-000 storage, a virus from the system hijacked its control and the system modified its function. Through the power and aura that Leon is unleashing, the blade was getting fueled by it. The red light that it originally has had turned into yellow before slowly being converted into blue. The temperature is getting higher and things beside Leon's radius is getting melted. To the great amazement of the fabric and quality of the clothes that Hee-sun advice him to wear, the clothes are not easily melted or lit into a fire.  
The intensity of the blade is getting stronger. His footsteps are becoming louder. Abkool couldn't understand. He seems confused of what is happening right now. But ignorance is also his sin he needed to pay for.
"That person told me, 'the devil will get killed and greatly incapacitated by this. Use this for the greater good and you will be rewarded!' But how in the world are you still standing human! Not only that! You got stronger than before!!! Infuriating! AHHHHH!" He screamed in pain when Leon strike his sword and Abkool's arm was sliced clean.  
Leon's face become distorted. The rage that is boiling in his head are slowly being released and hearing the laughter in his head didn't go well with it. He rather listen to Mint's voice than endure this nightmarish shrieks that had haunted him throughout his growing years.
"SHUT UP!" The earth shook in his voice. The mermen fallen to the ground and started to shiver. They could see now clearly. The prophecy is getting real. He had come to reap their dirtied soul! He had come to stop the injustice and filth in this land! 
Leon started to walk and every step he takes makes Abkool started to feel fear in his heart. Since he was young, he pride over his braveness that couldn't make him run like a coward from a great calamity. He is a chosen warrior of their tribe that accumulated many achievements. He has his brothers trust and the race's pride. But that changes today.  
His blood is dripping on the floor but he couldn't think of the pain coming from it. All in his heart bearing is fear of being reap by the reaper. The one they had made. He should have listened sooner. He should have agreed.
"Why are you infuriating me like this! What greatness that high nose of your gave you?!" Leon mockingly asked that made Abkool gulp. He gulps and he gulps more. He doesn't know what to reply and automatically his only arm and two legs started to retreat. In every step that Leon makes, Abkool moves back.  
"Great Warrior! Finish him! Kill him! End the calamity that said to be the doom of our race!" 
"SHUT UP!!!!" The mermen that is far behind Abkool became immovable. They are standing with that frozen expression in their face. When Abkool looked behind him in a rusty movement, he could see no glimmer in their eyes and that had frighten him.  
There is a prophecy that had told them by the priest. 
『When the ends of the world is coming, the devil will appear. He looks no different to ordinary human being but possesses power that no one could imagine. He will bump fates to the people indebted to him and betrayed him and no one can escape his judgment. For he is the disaster and the savior. A phenomena that cannot be stop no matter struggle one moves.』 
He knows it now. Abkool understand now. He doesn't know why the last thought in his head is like this when he should be caring more how to survive but why great ancestors? Why offended this God to the point of elimination?  
"You should have lived better..." Abkool didn't hear the next word when his heart stopped functioning and his mind only thinks of the sin of his race. Maybe if he could have heard it, he will put in a more hateful situation but seeing him not breathing made Leon struck the blade on the floor and made it as a support. He was in that position for a long time and even Crow doesn't have the heart to approach him. A new light had come to Crow and that is to not infuriate his master no matter what the circumstances is.