Help with a magic weapon

[Darklone]

Soo, I'm looking for some Critical improving mechanism...

The original weapon is a one handed slashing (1d8, crit 18-20/*2) Exotic Sword.

First question: Does anyone have magical properties that allow one to use an exotic weapon without the feat?

Second question: Anyone knows some balanced houserules for a heartseeker property to increase the critical multiplier of that weapon?

 

[Nightfall]

Firstly if its magical, you can just state in its properities, any one can use it or just a specific class, alignment, or race can use it as a martial weapon or without taking an extra feat. Secondly I'd say if you want a Heartseeker type weapon, have the creature that's being attack roll a Fortitude save. If it fails then the attack is considered to do double damage to it. Howse that?

 

[Darklone]

A Fort save for every crit? Hmm. Sounds nice. Perhaps some additional slashkin...