His damage was mitigated by Anger Rising massive armor, otherwise if he hit anyone else it would have been obscene damage. He sports 100+ armor all over.
Exactly, your "special privilege" as a war gladiator being able to wear heavy armor mitigated the "rage stacking". So a rage manager has to dump points into 3 skills and you have to wear some armor to prevent the above example. Seems like a pretty good deal to me if I were a war glad.

War's "stacking" works more indirectly I think. Heavy armor + create distance + tank/parry-x + hamstring, etc. They also have numerous skills that are always working for them the whole fight long and can't be blocked or prevented which makes them powerful.

Theatrics being the hybrid class they are depends a lot on how they are built. Looking at the skill tree it is obvious a defensive build could be troublesome: shield + medium armor + second wind + show off + parry-x. Offensively you obviously have signature move and GV that have been the main reason for many a loss in the arena.

If you are looking for the whirlwind of death and destruction recruit a rage gladiator because that just isn't what they teach in the other specialties.

I'd stop looking at skills in a one for one manor and instead step back and examine the big picture because when I do that things seem to be pretty balanced IMO.