It'd be awesome if they allowed us to transmog daggers to look like other 1h weapons, i'm a combat rogue and i've just started again after quitting at the end of wotlk, i was a bit sad to see they removed fast 1h weps, i can see why they did it but it just doesn't look very good.
http://www.wowhead.com/item=18805 it has a unique model which is really nice
and the most well known dagger
http://www.wowhead.com/item=18816 also kinda unique since only a quest ireward shares the same model
Or as someone previously mentioned; shard of azzinoth.
Also the crystal jaded dagger it's pretty huge.