Foreword: I have recovered some old files while tidying up my hard drives, stuff from the old days when I was into Dungeons & Dragons 3rd Edition. What follows is an unfinished article I originally meant to submit to Dragon magazine (when it was still a print magazine!) detailing a new rules option for D&D3/d20 System. Ehi, somebody still plays that stuff! I guess this works alright with Pathfinder etc., thus use it if you like it, and maybe build on it. It was never playtested (but, if you want my opinion, most such material released in magazines wasn’t, either).
Common rules: “variant” weapons, such as those described here, aren’t new exotic weapons – they’re special variations of existing simple or martial weapons. Any character proficient with the “base” weapon can use a variant weapon as it was a normal weapon of that kind, with no penalties to their attack roll (i.e. any character proficient with simple weapons can use a boarhunt spear as it was a normal longspear and a mail-piercing dagger as a common dagger). However, you also have the option to expend an Exotic Weapon Proficiency feat to perfect your use of the weapon, gaining access to a “special ability” unique to each variant weapon.
Boarhunt spear (variant longspear): a spear with a crossbar stoutly affixed one-third down its length, it is designed to stop a rampaging beast’s charge. When a trained user (Exotic Weapon Proficiency: boarhunt spear) makes a successful attack roll against a charging opponent (either as a readied attack or due to an attack of opportunity granted because of reach), she and the opponent also make an opposed strength check: a losing opponent is forced to halt the charge and stop in place.
Mail-piercing dagger (variant dagger): a strong, stoutly built thrusting dagger which only inflicts piercing damage, this weapon is designed with the purpose of punching through armor, chainmail especially. A trained user (Exotic Weapon Proficiency: mail-piercing dagger) gains a +2 circumstance bonus to hit with the mail-piercing dagger against opponents wearing metal armor (including: all heavy armor, all medium armor except hide, and chain shirt).
Afterword: my original file also has headers for two more weapons: the “swordbreaker” (variant greatclub) and the “long-reaching sword” (variant greatsword) – the headers only, but no actual descriptions. The hollow staff from this other article could also be one. If you like the concept, please, make up your own!