Alright, first I’m gonna show it to you here in case you haven’t seen the patch notes for 5.4 (full link here).
So this is going to blow the doors wide open on enchanting your gear, allowing any enchant to be cast on any item so long as it’s the appropriate type of item (you can’t enchant your chest with a weapon enchant and such, but all weapon enchants are available to all weapons unless there’s a two-handed requirement etc).
Since heirlooms are something that I place a high amount of focus on, even when I’m not actively playing the game like right now, this is a big deal that I do want to be able to cover everyone. That being said, until we’re able to do some testing on these changes it’s not going to be clear which enchants are the best for which items. So up until 5.4 goes live, consider my current Guide to Heirlooms to be correct on all fronts, but once 5.4 is out don’t believe the old guide in terms of enchanting until I’ve updated it with the results of testing.