Hey!, so i have unlocked and got the achievement unlocking all the different feral colour variations for the legion artifact (fangs of ashmane) but it only shows one colour. keep in mind this is a 120 boosted toon and it could have something to do with that
when i equip fangs of ashmane it changes to the different skin i want ( through appearance tab in seed of ages, but when i attempt to do the same in transmog it doesnt work)
Right click on the dagger selection in the xmog pane, and there’ll be a dropdown box.
This was a rough band-aid solution that is rectified in SL via the barber shop options.
when i right click it it only shows one colour 
as i said in the original post 
Ah, using the actual fangs. You’ll need to change at Order Hall, like all classes
wdym exactly, so i have a 2 handed staff currently - trying to xmog it into the fangs of ashmane but only one colour comes up when i right click it - i have the fangs of ashmane in my inventory and have changed the colour in the order hall but it didnt make a difference to the colour available at xmog >.>
realised i posted on wrong toon btw this is owrawr
Ok, you’ve equipped the staff, gone to the xmog pane (not the order hall).
Left clicked the weapon on character pane in xmog window, which will show fangs in the weapon selection on the right.
Right clicking on that should open a drop down. You may need to restart the game.
ofc it works now smh ahhaha. ur a legend dude <3
All good mate 
Enjoy