Being a caravan guard was not a terribly challenging job. The one requirement was the ability to be walk as fast as the wagons, which lumbered along at a speed most five-year olds could match. Actual weapons proficiency was useful, but not required. Those merchants with valuable goods, or vengeful enemies, brought their own personal guards. You were responsible for the animals and the caravan staff, not the goods. So guard came down to playing sentry, lobbing things at curious wild animals, and finding new ways to pass the time while walking.
Which is how Eulin found the secret to unlocking the knot-stone, and how we ended up running for our lives from a grumpy elder god, a barracks full of the Hounds of Winter, and not one, but three ambitious mages.