This intends to provide a streamlined mechanic to make magic items useable throughout the game within pre-decided boundaries (also, a money sink). The short version:
Every magic weapon can be attuned to a character's soul (PC's or NPC's) for a fee, which unlocks the ability of the weapon to increase its usefulness over time, only for that specific PC/NPC. Increase of usefulness happens over time from use. Tiered, as to spread the cost and rewards of the attunement over the duration of the game. Costly, to make the item feel more special. Also, very important, increases usability of weaker