It’d still work great there to provide a grab on their sword. Even large bastard swords aren’t all THAT much metal for how big the blades are. The blade catcher would likely only need to be as thick as dumb heavy display swords to be stronger than a typical sword back then.

When you spread a select few lbs of steel over several feet of length, it gets pretty thin. Something like this doesn’t have to be amazingly strong to still be stronger than any sword it’d meet. At least enough to catch and foul the blade without breaking.