I noticed a few things... If you don't have any Focused items they do not critical strike, ever. Their natural base Critical Strike is ZERO, nada, nothing! My companion has 7% medium armor, 7% aggressive, 3% passive increased damage (+17%) and 7 Shattered (9100 Penetration), still does not do full damage listed on abilities. I thought maybe the penetration amount was off so I raised it from 7 items (9100) to 8 (10400) and losing 1% aggressive, it did considerably less damage so that wasn't the problem. Here's what shows up:
Ability - Listed Damage / Actual damage
Warp Strike - 8946 / 8815
Life Siphon - 4473 / 4407
Razor Cape - 1789 / 1763
Impeccable Shot - 26839 / 26445