I just got the troll hero yesterday.
- unique apparreance
- regenerate 6 HP / turn
- lots of HP
- cannot use any armor
- cannot use any mount
The last point is very bad mid/late game, when all other heroes (and troops) starts going on horses or wrags, the troll slows them and I finish by letting him behind to defend my cities, too bad he is not a governor ...
As wild Trolls all get move 3, I think that this hero should also get it, this would make him more useful, and more able to keep with the armies.
Thanks for reading my suggestion.