Successfully blocking their attacks, Vincent counterattacked, swinging his swords and landing a strike on the bodies of two ghouls in the blink of an eye, ripping them into two halves. Then, he pounced on the others, killing them one by one, making them feel helpless and scared even though they were monsters!
Life energy is not pure and unique to oneself, and a person who directly absorbs the life force of another living being can face extreme pain or might even explode.
The life spell matrix absorbs and purifies the life force of the beings that Vincent kills, converting it into a purified version called experience points.
It's safe for Vincent to use experience points to strengthen himself.
One can not say the same for unpurified and chaotic life force.
