I went into the pskhanium with two eviscerators, one with 351 power and a damage bar about 25% full, another with 363 power and a damage bar about 50% full.
Hitting standard enemies, the two weapons did exactly the same damage. No difference at all.
On top of that, the weaker 351 power eviscerator had a +8% damage bonus against elite enemies. In practice, it was doing almost double the amount of damage the 363 power one was doing against elites. For instance, with the 363 power eviscerator, a revved up light attack to the torso of a bulwark did ~900 damage. With the 351 eviscerator, it would do ~1700 damage. It seems like someone put a / symbol where there should be a * symbol or vice versa.