As far as i know u can't enchant exploit... There is nothing 100% workable and that u can trust...
I've saw on one forum u buy any shield no grade u get scrolls no grade and enchant the shield till it brakes(your enchants need to be on F2,F3,F4,F5,F6,and so on..) and when it breakes u do it right quick, u click F1(u put on F1 the weapon enchant any grade u want) and enchant, they said it's 90% times workable, don't works...
I've heard about enchant weapon then go kill bit then enchant again, don't works
I've heard about enchant when u are experiencing item server lag, well, that worked before for some weeks and very hard to do it... Don't work anymore.
Some times ago we could enchant and if it breaks we teleport on second to any city and on middle of teleport we turn off computer and it rollback like 10 seconds, we still had the weapon, don't work anymore, items not rerolled(That worked for items drops on karma and duping items, was great at that time

)
Well, it's all about luck 0_o