[Cerek the Barbaric]

Felix,

I suppose the simplest answer to your question is - Yes, they will be cumulative.

The long sword proficiency means you are REALLY good with a long sword.

The two-weapon proficiency is a fighting sytle. There is a substantial penalty for trying to fight with two weapons without this proficiency. Your THAC0 (or "to hit" roll) suffers a penalty which would offset your long sword proficiency. By adding "*"'s in two weapon proficiency, you will reduce these penalties.

Even with 5 "*"'s I think you will still suffer a -2 penalty in your "off-hand" (the weapon in your shield slot). This would be subtracted from your long sword bonus, so you would still have a good chance of hitting with that sword, but NOT as good a chance as you have with the long sword in your other hand.

I hope that answers your question sufficiently.