Article:
D&D 4th ed: Self inflicted curse items.

Today I present you with two new types of magical items. The theme for these is 'Self Cursed', which means, the items could be harmless if used with caution, but when in the hands of your average player character, they can be quite dangerous.

First, there is the Life Powered Weapon, which can be any basic magical item of an appropriate level for the player characters to find, but has the added ability to heal another, or spit a fire ball, or turn the wielder invisible for a while, at the cost of one healing surge.

The item's additional power is up to you, but I do suggest something very attractive to the player, something that they will want to use as often as they can, and a ranged magical attack for a melee fighter is like tank catnip! I suggest you tailor the power to suit whoever is using the item. So, invisibility for the rogue, shield of protective force for the wizard, that sort of thing.
And here is the kicker.. this is not a limited ability, the character could spend all of the healing surges they have on shooting fire balls or trying to heal others.
This has two immediate effects on game play.
First, the character can become an awesome force in the game world, cleaving through enemies while hurling balls of fire, giving that tactical edge all players crave.
Second, the more awesome the characters behavior, the higher the risk that it could all go horribly wrong.
After all, this weapon is powered by their own life force, each use of it's special powers has a cumulative weakening effect, increasing the chance that the character might be caught with no healing surges left, far sooner than they normally would be.
And all they had to do to avoid this, was not use the item excessively.

The second type of item is the Phylactery Weapon, which allows the wielder to drain additional hit points from wounded enemies, store them within a gemstone set into the weapon, and use those points later to heal others, or themselves, or, most importantly, to inflict even greater damage with the weapon.