Dr Simon
Explorer
How do you like soulblade idea?
Seems okay, if somewhat complicated for what you get. In the past I've used a simple variant, which is this:
The Bonded Item feat may be taken by any character of 3rd level or above, provided that they have used the item in question through several dangerous situations (and it has made a difference). A bonded item gives a +1 enhancement bonus to its 'normal use'. Most common would be a weapon, gaining this bonus to attack. A suit of armour may also benefit but other items such as thieves tools, rope, artists brushes and so forth are all candidates. Once bonded, the wielder can also spend XP to add further enhancements to the bonded item. Thus a bonded sword can gain further bonuses or special abilities. Obviously this is easier to adjudicate for weapons and armour but imagination can be applied to other equipment.
This means that, for example, swords become legendary because of who wields them, not who made them.
Losing a bonded item may or may not be a real pain. They should be fixable, with maybe a monetary cost for the ceremonial materials. Still on the subject of swords, that gives you a quest to retrieve the Green Destiny sword, or to reforge the Sword That Was Broken etc.
Doesn't give you intelligent items, as such, though.