The simple question is - Should items that are crafted by players be the best items in the game that you can find/make, or should the ones that drop off of raid bosses be the best? How powerfull should bound items be compared to regular ones, considering they have an expiration time.
How should loot be split among the drop boss list?
How should bound weapons behave?
Examples of rare raid ingredients would be something along the lines of Daedric Named Grand Soul gems of the dead Boss, Special unique crafting items like "the eye/bone/scale/bodypart of the dead Boss", hard to come by ore/bars like aetherium bars etc.