How to counter mind control spells (subjugation, blinding, etc.) used by a Necromancer?

removing enchantments and cleansing was ineffective in half the cases because his magic skill was 1.5 to 2 times higher than mine (this is always the case because it's his main skill + education).

The magic parameter does not affect "Remove Enchantment" - the level of the spellcaster is the deciding factor (see the manual for more details). Even if he has "Spellcasting" (expert), you (with "Soldier's Luck") will have several attempts to remove his "Dominate". Try this build: Light (Storm - Secrets of Light), Attack (BB), Defense, Luck (Magic, Soldier's). And for dessert, either Leadership or Education. Try my build and let me know the results.