As you know some of the classes have specialized gear, ie the thief with a ninja mask or hood. You can take these off a new character and put them into an old character. Or you can even have rangers running around with hoods, or thieves running around with engy glasses.
First you must have a transmutation stone. Easy to find they come from map completions or black lion chests or market.
1.) Make a new thief with hood.
2.) Buy a mask on current character
5.) Now you can transmute the mask into hood.
6.) Put the new transmuted hood into bank
7.) Go into your current thief and then take out the transmuted hood.
8.) Now you can transmute the hood with any mask
Note: It will say it's soulbound but you can still move it to another bank no problem. I have my engineer running a hood! Enjoy!