I had an idea but never really got to implement it.
I basically designed a sword with several powers so it had a total bonus of +10. But to activate each power certain tasks needed to be accomplished. The idea was that the character's 'share of future' treasures would include the advances in the weapon's ability.
Once the wielder slew a fire elemental with the sword, the sword's ability to flame was activated (And this would be obvious to the wielder). The sword had a history and the character could learn about it in various ways, thus he could sort of plan to improve the blade (seek out certain challenges to improve it).
I had to talk to the player about the treasure thing. Luckily he was a sport, and appreciated the specialness of the sword. So when treasure divyng time came about he was prepared to say "I'll sit out of the first round, since I just discovered this new feature of my blade."
I think it would've worked out well. But it is tricky to manage and quite informal.