Benefits of an invisible sword?

[Theo R Cwithin]

Even if the enemy "figured it out" he still wouldn't know the exact shape of the sword.

Right, which is why the invisible weapon has a minimum bonus of +1 in my proposal.

Wouldn't he? We're effectively talking about supermen here Seems to me a trained warrior would very quickly figure out the sword's length and whether it's a slashy or stabby weapon after a handful of attacks. Ultimately, the fight is about who's the better swordsman, not who has the better sword.

Consider: I would guess that Blindfight nullifies all advantages of an invisible weapon, as it's geared toward entirely invisible opponents, not just weapons, right? Thus, the invisible weapon alone provides significantly less advantage than the feat is meant to negate.... and so completely negating the weapon's advantages should require less than a feat's worth of character outlay. In other words, negating the invisible weapon's advantages should be doable without this feat (and this feat is an "entry level" general feat, with no prereqs!).

So I'll revise my previous suggestion: I think it should be even easier to counter, using a spot check (as irdeggman suggested); a countdown (advantage goes away after X rounds); a dice pool (eg, roll BAB d6s every round, as soon as you roll a 6, it stops being an issue); or something similar.