Only one character needs to put 1 point in loremaster, the rest comes from two rings, amulet and the trait materialistic. More then 5 loremaster is worthless.
You can't trade talents on the henchmen so may still consider Know-it-All. Also one may prefer one more AP or more HP but I aim for a reliable way to apply the status effects from spells (high INT) especially at the end of the game when melee damage takes a lead and the mage role is more control then damage. The more you progress in the game it becomes easier so don't worry too much.