When I logged in today and reset my morphs on my Stamina Nightblade because Siphoning Strikes restored Magicka instead of Stamina (wrong morph for the new skill), I found that the morph reset de-leveled several of my long time, fully leveled skills, all of which are weapon skills. Poison Arrow was completely reset down to level 1 when I used to have a fully leveled Poison Injection, and Twin Slashes was de-leveled to an un-morphable level 3.