Grappling with an invisible opponent

[Nareau]

Let's say an Improved Invisible attacker decides to grapple with a character. The character decides to fight back, stabbing at the attacker with a dagger. Is there anything in the rules to suggest that they would not suffer the 50% miss chance due to concealment? Logically, I think it should be easier to stab at someone that you can feel. But I can't find anything in the rules to support this.
If there isn't anything in the rules about it, how would you deal with it? Should the concealment be totally negated? Reduced?

Thanks,
Spider

 

[Hypersmurf]

If there isn't anything in the rules about it, how would you deal with it? Should the concealment be totally negated? Reduced?

The conecealment is 'reduced' in that they automatically pinpoint the right square. The miss chance remains.

Mind you, I rule that the miss chance applies to a character with no Darkvision who has been Swallowed Whole as well.

-Hyp.

 

[Hypersmurf]

conecealement: n. An object, such as a tower shield, that provides Cover from a Cone of Cold.

-Hyp.