The 12 gauge ammo attached to Becker's vest are dummy rounds used for training purposes, clearly not live ammo.
The sword that Sir William uses has no honed edge and is actually little better than a metal club. It could certainly bruise and batter, but when he puts the point against Connor's neck, it is easy to see that the edge of the blade is rounded, not sharp, not does the tip taper to a sharp point.
There are two problems with the events as depicted, both related to communication. Sir William's speech would have been either an archaic form of Middle English, barely intelligible to modern-day Britons, or he would have been speaking French, which was usual for the English upper classes until the middle to end of the fourteenth century (no kings of England used English as a language of governance from 1066 until 1352 [see Trivia]). Sarah would have had similar difficulty making herself understood to the people of the past.