For what it's worth, I'm officially in the "It's Overpowered" boat.
Looking over some of the fight logs, it's just bizarre. I have the 8th largest ELB in the game, backed by a decent amount of strength (5.3 mil). But a single hit from a large ExBow levels me down to -3.67 million STR. A single hit. That means the archer's damage from that point on is negligible... say, 70-400 damage per hit.
This isn't a case of "woe is me," as I use a 3-pronged attack that can level most specialized teams at or below my MPR. Even with my archer neutralized, I can still win most of the time against ExBow teams (even when they use RoBF).
But the ability for a single hit to completely decimate 9 million levels of anything is insane. The item serves a greatly needed purpose in this game, and I like that it forces single archers to consider using dual damage dealers, but it should require a serious EXP investment to make it really work.
Cap the reduction per hit. Make people hit three or four times before utterly crippling 9 million levels. I hate to admit it... mostly because it will go to his head... but Ranger is right.