vaunce means to advance (various senses). Lexicurio rates it Sui generis — a strength score of 87 out of 100.
verb
- To advance (various senses).“Then tooke the bold Sir Satyrane in hand
An huge great speare , such as he wont to wield ,
And , vauncing forth from all the other band Of knights ,
addrest his maiden-headed shield”