Here's the problem with a sword:
Rubber Knives can hurt if there is enough momentum from the attacker and/or the victim.
A rubber sword will have a fair amount of weight to it, and therefore, if swung, will hurt and/or be able to remove the goggles of victim.
Anything which can remove someones eye wear is a hazard and should be weighed heavily against by the organizer.
Personally, the only advantage I'd see with having a sword is length of the weapon, which is a pro heavily outweighed by the cons of having to carry it, inability to draw from close quarters, potential for injury of both parties, and the fact that more often then not it's easier to just shoot the guy.
Having said this, I'll always have a rubber knife on me, because when the opportunity to kill 5 guys with their backs to you arises, it's really fun.
Ár skal rísa, sá er annars vill
fé eða fjör hafa. Sjaldan liggjandi úlfur
lær um getur né sofandi maður sigur.