Higher level res increases the amount healed when resurrecting. While it's okay to leave it at 1 at earlier levels, its better to just raise it to 5 during later levels so the person ressed will res with more HP.
EDIT: Level 1 res is next to useless - in a situation where you're surrounded by aggro and if you use level 1 res, he'll res with like 10% of HP, and probably die in one hit. -3% EXP. It also has a cooldown of 10 seconds, which means you cannot heal for 10 sec.
Last edited by Kotarou; 10-07-2009 at 06:15 PM.