Enchantments are from Runes and also occur naturally. The full range is available.
While it doesn't affect the Undead, the living will have a cursed item that acts as if it is a lower level weapon, that also cannot be taken off their equip slot. To get rid of cursed items, cast a rune of null on it, a rune of teleport, or a portal rune. To avoid equipping cursed items, equip them to the minion or identify the armor/weapon - you will be notified of the curse and can unequip it from your minion.
Causes massive knockback occasionally, and is never cursed. You can get blessed items by using a rune of holy on them, obtaining blessed items from RNG and with much luck it can be found on chests