A lot of skills you need, but just 1 point will generally suffice.
Repair: Unless the item has a particularly low durability (those pesky 1/1 items), you can keep anything functional with a point spent in this skill. Don't bother having people repair your stuff; it'll soak you for $ in no time.
Alchemy: A point should probably do it, 2 tops. Minor restorations fill up 50% of your mana and health, and you can make those from easily bought minor healing and magic potions. 2 points, and you can make your own minor healing and magic potions... provided you have vials. Out of curiousity, what do you do with the vials when you mix two potions or drink one?
Poison weapon: 1-2 points. Useless later in the game, tapping an orc with a poisonous stick and just running off works wonders.
Skeletal Wall: 1 point. It's a great distraction skill; there's 5 of them, and since they're the new target on the block, your foes will fight them immediately, and leave you alone. Consider it a "Look over there!" skill to get the heat off of yourself.
Reflect missiles: 1 point. For some reason, this seems to work much better than it is supposed to. Additionally, if you have a poisoned weapon handy, every arrow that bounces off of you will take away one poison charge, and you can kill those pesky elite crossbow orcs by just standing around and being a pincushion.
Elven sight: 1-2 points is enough to see everybody around you.
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