What do i do with uneeded untradable legendarys?

Title says it all

 

If it's equipment or gear you don't plan on using soon, you can sell it to the blacksmith or keep it in your account bank in the case a future character/class will need it. If it's trinkets from the Festivals however, then I'd keep them in your Misc Bucket as a neat thing to keep, especially if it's a utility trinket as it can provide bonuses for a tough boss fight if you need those in the future.