Zahrym quoted earlier on his official twitter account that in 5.2 they will be removing main hand/off hand restrictions to weapons for transmog. Also most likely it will be possible to transmog a sword - axe - mace etc. So stocking up on weapons that where earlier useless cause of main hand slot, or making most weapons generally more valuable as every kind can be used at the same time.
http://www.wowhead.com/item=31336/blade-of-wizardry
Blade of Wizardy is a great example of how you can earn some easy cash by doing this. Its according to the Undermine Journal it's price is on most servers around 1k-5k. Why? Cause its main-hand only. After this change the price will SKYROCKET as its a red lazer sword which are usable in all hands. Even as 1 hand mace and axe aswell.
Tip from DanteLarka: Want a blue lazorsword that are currently main-hand only and are pretty easy to obtain as its a BoP from a TBC dungeon. Get the Spellfire Longsword http://www.wowhead.com/item=24361/spellfire-longsword
Sorry for the messed up post, still tweaking and trying to learn how to use basic forums modifiers...