http://www.lineage2.com/Knowledge/cp.html
After reading the info page on the sword it made me think some.
"All monsters in the world have the potential to drop it."
In this case, a level 15 character could in fact gain the weapon.
"A player carrying Zariche cannot attack players that are level 20 or lower. In the same respect, players must be level 21 or higher to attack the character wielding Zariche."
This means a toon who gets the sword at level 15 can't attack people around his level nor can he be attacked by them. Bit unfair isn't it?
Additionally, "When a Hero acquires Zariche, skills designed for Heroes may still be used. The player can use these skills again when Zariche disappears."
Isn't that just saying the same thing in two different ways?