Ok, for the sake of the thread, lets not talk about spears.
Probably a good idea, let's not derail this, and besides, it would be stupid to assume that crafting would let you make items not even similar to ones you can get through other means.
I do think crafting and such should be divided. just because I can fletch a bow doesnt mean I should be able to make a shield, or a sword.
Blacksmithing, Fletching, it shouldn't be just one base skill, it just doesn't make sense.
That's not going to happen, it would require too many skills. There's three crafting skills, one for each category, and they are smithing, alchemy and enchanting, no more, no less. I'd imagine smithing applies to all weapons and armor you can craft, alchemy is obviously used to make potions, and enchanting likely means enchanting mundane items, like it did in Morrowind, though the system may be different. Although I could certainly see perks being used to allow you to further specialize in certain areas of crafting, like under smithing, you might have seperate perks for crafting melee weapons, crafting bows and arrows, and crafting armors, or it could be more specific than that.
Though crafting won't allow you to make anything you could possibly imagine, we can safely assume you'll be limited by what items are available for crafting, at least for smithing (Alchemy quite possibly works like in past games where you just mix ingredients that share effects and produce a potion whose strength and duration is determined by you're skill and the quality of you're apparatus, or maybe they changed it, we'll see.), it's just a question of how large the list of available items is.