Whirlwind is useful for breaking crates and such. And honestly I've encountered instances where some extra damage from it would've been nice, but the damage is additive: 1.5, 6, etc, so whether you do 1 damage or 1000 damage, it's still adding the same. Unlike Poison Arrows and especially Fireball, which are completely useless, Whirlwind does still have uses in battle, even at Lv1.
As for stuff like mindread and the weapon skills, I always interpreted having a skill point in them as enabling them, period. Other skills have zero effect if you have no points in them, so technically, no points in say, single handed weapon expertise would mean you are unable to fight single-handedly (or even equip just 1 weapon) altogether. Considering single handed is necessary to use sword+shield and dual wield, and unarmed is necessary just to remove weapons, you need those weapon expertises anyways.
