I just want to add, because it doesn't seem to have been pointed out/discovered/mentioned, that Fierce Attacker gives the npc Counter Attack.
I normally don't notice this because well, lets face it, when exping with my npc, the only way she gets hit is if there's some kind of aoe because otherwise im taking all the damage and she just doesn't do enough to pull hate. However, when I do the Tactic's Pearl quests every week I go in as pld/war to tank while she does dmg, she does damned amazing damage on them hit for hit and WS wise (the strong WS's that is), and I noticed that when she got hate and started getting hit she was actually counter attacking a good deal. As far as I know Attacker mode doesn't have counter-attack, it's pretty much a Warrior. Seems Fierce Attacker is War/Mnk, that or it may just have the counter attack ability (along with who knows what else that may not be working properly).