I was playing an alt to explore some of the newbie quests I never did, and one of the DMs sent a tell warning me that excessive weapon swapping is considered an exploit, especially for melee weapons.

It's be nice to see that in the FAQ, as in other games it's considered something of a key skill for fighters to have.

I was informed that "Ranged->melee"is of course fine, but by the same logic of swapping to defend, I'd think "Two-hander->1H and shield" would make sense if you "drop" the 2h or something like that, and don't re-equip it until you have a reasonable breather.

So really, what's excessive? Swapping mid combat, or is "swapping down" to a defence set alright if I don't then go back to the first one?

It is excessive if you are doing so to acquire extra attacks per round. Wait until the round is finished before you decide to choose another weapon. (Which is cheating and most definitely an exploit.)

Oh, right. I didn't realise that was possible, and the reason for the tell. I thought that swapping to gain a better defence if surrounded or whatever was considered an exploit somehow. Worst I did was swap back to a 2h to finish off the last survivor.

In that case I'll bear it in mind and only swap when I really need to. I dont' want to be lame.

Swapping once to a shield and sword mid-combat is ridiculous to me, but won't get you banned. However, like sherry said, pretty much anything more than that is cheating and we'll ask you to find a new server to play on if you'd like to continue playing NWN.

As an aside, I want to add that it's Frequently Asked Questions, not Complete List of Things You Can't Do. This isn't something that ever really comes up, so it isn't covered.