It is not from gear. It is a combination of additives. Similar to though not exactly all of: frenzy, ferocity, lesser form ferocity, blood frenzy, berserk, brutality of the shark, beastial fury, enrage, feral growl, dragon's strength, wardance, chestbeat, and/or aristaeia.

The comment about enhanced damage does make some sense, though I wouldn't have figured it to be such a large factor. A shapeshifter's damage output already goes way down if their strength is hindered, similarly dodge and dexterity, regeneration and constitution.

From what I've noticed, they play very similar to warriors except they don't get to choose their specs, have a much smaller hp/skill pool, can only sustain their combat abilities for certain periods of time and can't call for help during fights, along with all the other things I noted. To compensate, they're given some magical advantages like 'word of recall' and access to wands. Without going into something akin to a rant, I just think it's weird that they give up so much for only a mid-level power ceiling even if someone puts in an enormous effort.