Yes, Jaes is not THE BEST mage. Flat. Others do his Job better and he needs equippment to really shine. All Armors that deny rune usage (to get something out of his ability) are expensive and hard to get your fingers on. Also, to equip him with a mana weave leads to discussion with everyone else wanting to have it provided, you finally got it.
BUT, IF you equip him with mana weave and a runeweapon, you suddenly look at a movement:4, health:12 (!!) Fatigue:5 Mage, which is clearly above average. with a good armor you can play him as a meelee mage (which is crazy as runemaster), hell, even as a tank.
This is hard to get on and clearly not an easy peasy play style, but it offers some nice alternate gamestyles and is quite cool when you play a one-shot expert gamemode!
i got to tell you it is nuts, when you perform 3 attacks 13+ damage in 1 turn!!