I spent a few minutes test “cutting” with my rapier today. Nothing but wrist and elbow cuts, the shoulder and body were not used at all in these actions.
If you look closely in the first picture you can see the cuts from the short blade along the back edge. With the long blade I find that he cuts feel better when they come in high, near the 6’ mark, while the short blade wants to cut closer to shoulder level.
This was done with a perfectly blunt Darkwood bated rapier blade, the same model that countless people use for SCA and AE use for fencing. So tell me again how rapiers can’t cut.