I think that's probably based on the story line about Lancelot wounding Gawain with Balin's sword. Somewhere in Morte d'Arthur, but I don't recall the "wait to

I think that's probably based on the story line about Lancelot wounding Gawain with Balin's sword. Somewhere in Morte d'Arthur, but I don't recall the "wait to be at his best" part. It sounds like a Hollywood addition to the story, so maybe a movie?