Grimrock

For example, if you increase ice magic several points - getting listed bonuses such as 'DEX +1' - are those listed bonuses the only benefit, or does raising the skill have other benefits as well?

So, if you see the benefits above a certain point and say 'those don't seem worth it', does raising it also cause more damage?

For both weapon and magic skills, raising the skill level will also increase damage, though the game doesn't outright say so. Actually I don't know if it increases damage outright, or raises the upper limit of damage, or just increases weapon accuracy.

In case of weapons, each point in weapon skill (swords/unarmed/mace/axe/dagger/missile/throwing) increase both Attack Power and Accuracy in given weapon.

EDIT: of course, as pointed out by Daniel below, in case of Throwing and Missile Weapons only Attack Power is increased

Missile/throwing auto hit of course, so they don't get an accuracy bonus.

Daniel.

OK, thanks. So even if I feel like air magic bonuses stop being very useful at 27 or 32, it can be worth going to 50 or more instead of switching to another school or even the neutral energy one.

You can see the weapon damage and accuracy increase below the holding hand. I presume the magic increases damage by a similar amount, but this isn't displayed anywhere.