So if you have a destruction skill of 1 but chanto skill of 100 and create 10 scrolls that shoot 100dmg fireballs this is the problem; they do not have a magic cost to use the scrolls so you could create a 1000 damage 100 radius scroll that raqes the world with no mana cost. This effectively makes chanting>all other magical classes.
You pretty much stock up on really light (wieght) scrolls that are totally op and [censored] the world.
Yep. But first you have to get 100 enchanting, find powerful enough souls to make the enchantments, and scrolls go away after one use. By the time you get enchanting to 100, you could have chosen to get destruction to 100 and then pwn the world that way with spells that don't go away after one use. Getting to 100 enchanting isn't going to be a cake walk either, it would be just like any other skill. You'd get better as you use it. Early scrolls and other enchantments are going to be lack luster at best, cause your just getting your feet wet.
The reason there is no magic cost is cause the scrolls go away after one use. You could use that super powered soul to enchant a sword to deal more damage and that damage would have stayed with you for the rest of its use, but you chose to put it into a scroll.
You'd still work in other schools of magic so you could gain spells that cost magic instead of expencive souls. Magic is free, you get it back after resting or as time passes. Powerful souls are not free, and can be hard to come by.
As for weight...do normal spells weigh anything at all? If you're well stocked on scrolls, you'd have less room for other stuff. And for a mage character who lacks the str to carry that much, that could mean a lot.