1) How long has been your friend playing a Warrior?
2) A warrior is highly dependent on gear for his dps, tanking
3) Nothing wrong for a warrior to roll on a mace or a dagger.
4) Mace spec is the best pvp spec for warrior
5) Dagger is good for tanking in a way, the atk spd is fast.

All in all, in general consensus a dagger should go to a rogue IF a dagger rogue needs it.

As what i see in your write up, tanking non-elites in crypt? nothing wrong with dual wielding, but if what you say is true bout your friend having difficulties on non-elites....QQ

Comparing to druids before the latest patch.

1) Druid dps > warriors
2) Druids threat generation > warriors
3) Druids tanking > Warriors

Who don't like a 22k armor tank with 16-17k hp, running around, with mangle that crits like cake and generate aggro with a breeze.