Professional mountain climbers need to learn to speak proper English then Ebbie :)
Summit is a noun, summitted is a made up word which has come into regular use. It is claimed to be the past tense of summit, as in to 'summit' a mountain [sic]
However it's not good grammar, and as I said it's a noun. Remember the mantra.

"Is there no noun that cannot be verbed?"

J :)