Following the common sense, sturdy knight should be able to carry much more weight, than subtle adventurer (vise versa, >800 and <300 )
And intelligent Mage is too assailable even to agressive plants for now (plus fireballs hurt the hero himself if enemies as homunculus are close). Could you make special "armor" for this hero as for other two? How about giving on start a "Robe of mages", which allows to leap to any cell of the combat field, even if enemies nearby block player. Also, i think that Mage should be able to throw projectiles not just along straight lines, but to any enemy aswell.. I suggest basic wands to deal damage only on one cell, but Mage can be the hero which is allowed to use scrolls during combat: average scrolls deal dmg at pointed cell and 4 cells near it (basic cross), and legendary scrolls deal dmg pointed cell and 8 cells around it (circlic blast which splashes on 9 cells).
While adventurer (and especially knight) have some assortment for them in armor to wear, why not add (besides robes of mages) majestic absorbing cloaks, which greatly diminishes items' weight and makes Mage's carrying limit literally unlimited.
P.S. What about those perks you wanted to add after exams ;_; ?