For example, he could swing his staff menacingly to intimidate.
He could hold up a bag of coin and a drawing of a person being looked for, to make a negotiation.
Being mute is a heavy penalty by default. Either you want to play a mute character and have a heavy penalty or you're not taking the implications of being mute very seriously. If you want to be a mute character, but just on situations that doesn't penalize you too much, I think the experience of playing a mute character is not what you're looking at. As I said, in such a situation, using muteness as a "character skin" would be much better, and also free [MENTION=6872920]LF219[/MENTION] to focus attention somewhere else.
Trying to argue that his intention was that he wanted penalty that didn't allow him to cast is absolutely refuted by his own words.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.