Gleipnir tried to find out what's going on and the truth made it pale, "Poison?"
It could feel something crawling inside its body and the process was slow, also.
Just like the poison inside Sylvianna's body.
"Do you really think that you're already smart that you put a poison on the sharps of your blade?" Sylvianna managed to smirk, "The poison in your body is already spreading throughout your body and unless you get the antidote in my possession, you are destined to die a pain you wouldn't even imagine exist."
When Sylvianna aimed for the enemy's heart a while ago, that laser beam contained a milligram of poison lethal for monsters like Gleipnir. Although the effect was delayed due to the constraints inside Gleipnir's body, the end effect was the same.
Now, both of them were poisoned and unless treated, they would eventually die.