Of course, no castle parapet was complete without a cordless drill.
You have to think time traveler.
Imagine he was in his shop, wherein he had a few fully charged batteries for it, putting the final touches on his new full auto crossbow, when a strange blue streak of lightning struck. Next thing he knew, he woke up with a blazing headache. He and his shop were now in the middle of an open field. All he can see as he steps out the door is the distant silhouette of a Medieval castle.
It seems he's been thrust back in time to Dark Ages Germania, and word has it (he's able to make out what passes for German in this age) that the Huns are preparing another assault.
