Spectral Hand and Greater Invisibility.

[Numarak]

If a caster gets invisible as per the Greater Invisibility spell, and then casts Spectral Hand, and the target of her attacks can not see invisible, does the caster get the benefits of being invisible when attacking with the Spectral Hand to such an enemy? -no DEX bonus to AC, +2 on attacks- Or he does not since the hand is not itself invisible?

My guess is that since the attacker is invisible and the Spectral Hand is just the vehicle to deliver the attacks, the caster gets the benefits, but on the other hand, being the spectral hand visible, I could be wrong.

[Purple Dragon Knight]

Nope. The spectral hand screws up your plans in this case. You have to go deliver your touch spells personally, toe-to-toe to benefit from invisibility. Or shoot a ray, and arrow, or use a melee weapon. The hand is visible.

[Numarak]

So just to get it right, if I'm an archer and I'm invisible, the arrows I shoot turn visible, but it doesn't matter, I keep the benefits. If I cast a ray, the ray is visible but as long as I'm invisible, it's ok, but, if I use a visible hand, although I'm invisible like the other cases (archer, and ray shooter), in this case, the hand turns me visible and then the target retains her DEX to AC?

The rules for invisibility specify about invisible attacker, not invisible weapon. Why is it different in the case of Spectral Hand than arrows or rays?

[QuidEst]

I'm not sure which way it works under a strict interpretation of the rules. The reason it would possibly be different is that rather than firing something that turns visible, you are attacking with something that is already visible, so they've already got their eye on it. (It's also a bad idea, because Spectral Hand announces to everybody exactly what square you're in. Expect flour, glitter, or other things targeting your square.)

On the other hand, the spell specifies that it counts normally as an attack, so granting invisibility bonuses would be a reasonable interpretation. I would probably consider that to be RAW. I would expect some variations in how GMs choose to handle this.