From my perspective, I never bother with:
*armorer - I find it easier to just have my equipment repaired, plus I usually carry more than one weapon anyway (CE bound weapons are always handy
*mercantile - Apart from the fact that this skill is bugged, it's not exactly difficult to acquire cash in the game. If I'm going to try buying and selling to maximum profit, I'd rather just use admire or bribe to raise a merchant's disposition.
*spear - Simply.... why? There are so many superior weapons to play with..
Others?