Egg someone on

Hi! I think I know what this means, but where did the phrase come from? Thank you - Saxon

It's an Old English word, egge, derived from Old Norse and (eventually) the L**in and G**ek roots acer and acme, meaning sharp and point. Egge meant the sharp edge (also a related word) of a sword blade. If you're going to egg someone on, poking them with a sword will usually prove effectively motivational.