Game Mechanics: Caster melee skills only raising 3 pts per level

[Remeygi]

Hey there

I am currently playing a human wizard, level 10, levelling her without casting - only using melee skills (yeah, I wanted to try something different).
It seems as if my melee skills only can be raised by 3 skill points per level (at level 10 I stay at a skill of 33 in 1hb, 2hb, piercing and hand-to-hand and can not raise these skills at the trainer any further.
I always thought that any skills can be raised by 5 points per level.
Don‘t think this is classic. Seems like a bug to me.

Cheers,