I checked and I do not think that it drastically reduces your weapon's durability. I do, however think that durability is reduced with ever contact of an object. So I do think it might, but just as much as the standard durability drop for fighting enemies.
You can take this with a grain of salt.
I can tell you now that when I was randomly trying out the whip the first time, I had to repair it afterwards. I hit a couple walls but no enemies, just seeing various attacks. It does count towards degradation of your weapon, but it isn't a lot so don't
worry too much about it. You'll get a warning if the durability gets too low, though.
Yeah and those acid spitting centiped things down in the demon ruins broke my blacknights sword very quickly, thankfully though you dont loose the weapon when it breaks you just have to repair it, I panicked at first because that particular sword is +5 2
handed it kiled the pinwheel boss in 3 hits lol.