update: i tested the Y variant, and it seems alot more powerful, where the normal one does around 8-10k dmg, the Y did 20k plus dmg

My theory is that the normal one limits ur dmg to only 1.5x normal dmg without crit, and also limits ur crits to only 75% of the enemies. This means that its probably better against stronger opponents but worse against weaker ones. whereas the Y either increases injury or crit by 45%, not sure. Perhaps someone who knows these answers can confirm it