and even if i could be dumb enough to sell it, i checked every vendor in arnika (i've been only there since when i obtained the wheel key) MINUTES after losing it (had a previous saved game)
i even checked the roads between arnika and the monastery, without luck...
i think only an editor could save meand i don't care if it wasn't "an item required to finish the game": i was playing that way and i want to keep it