Not really. It just means he's worked really hard at it, compared to the barbarian, to whom it comes more naturally.
Speaking of hard restrictions, its been a LONG time since they've had those in D&D, definitely gotta go back an edition (i played 3rd to death). In 3rd edition, all it did was give you a spellcasting failure % based on how easily you can make the arcane gestures while wearing armor. For example, a chain shirt affected you much, much less than a suit of Fullplate. This seems like something that could make a similar translation to JADE, if TB's interpretation of magic involves more than the invocations of power. And there should certainly be no weapon restrictions, because it makes no sense, as other have stated before. I remember playing several classes in the aforementioned system that actually have special abilities revolving around the skill they gain using armor, reducing the penalties associated with its use with arcane magic.
On the whole cleric thing, that's just the difference in magic =p Archetypical Clerical magic are sort of like prayers to the gods, while arcane magic is more like straight from the elements, or the world, itself in a way. In any case, I stand by "hard restrictions bad, soft restrictions good".
I think a balancing act between armor weight would be useful in all aspects. Like similar to D&D, to wear heavier armor and gain the heavier protection, you have to sacrifice some of your mobility. It makes sense to me, and would be awesome (only if its not a pain to code, ofc!)
Normal - GE Ranger, Human Monk, GE Wizard, Hurthling Beastfighter, Hurthling Farmer
Ultra - ULE GE Wizard