So a fully kitted out character could have a half-dozen different effects firing on a natural 20.
Yet there are nineteen other numbers on that dice - how about spreading the love?
This weapon is blessed by Dol Dorn, and deals an additional 1d6 force damage on a successful attack roll of a natural 19.
Unlucky for some
The Traveler has infused this weapon with an unusual curse. When an opponent is struck on a natural 13 attack roll, the target has the [improved] curse spell cast on them.
Better luck next time
Misfortune strikes even the best warriors; Olladra has blessed this weapon to help even the odds. On an attack roll of a natural 1, this weapon gives the weilder a stacking +1 to-hit bonus, which lasts for 6 seconds.
The possibilities are endless!