In the bukkit plugin Zephyrus, what does the LifeSuck enchantment do?

I'm not familiar with that plugin, but I'm 99.9% sure that the enchantment you speak of is a form of Life Steal. Try losing a few HP and using the item that's enchanted with it to hit a mob. Fall damage is the easiest to recover from if you fell like 7 blocks (you can survive a 21 block tall fall apparently).