Thread:ChishioKunrin/@comment-25936766-20170806031817/@comment-4010415-20170806033635

Basically, the point I was trying to make is that Pyrrha took a spear and made it double as a xiphos, thus basically giving a spear a sword blade, which made it useful for both the stabbing of a spear and the slashing of a sword. Comparatively, Weiss took a rapier and decided to make it bladed like a normal sword while still retaining the stabbing point at the tip, thus turning it into a rapier that can slash like a sword. That is why it isn't utterly ridiculous that she slashes with it, and it's not like slashing with a needle. Yes, it would be nice to see her do more stabbing and thrusting, as it kind of defeats the purpose of customizing a rapier if she won't use the actual rapier part of it, but we still have the fact that she custom made it to be useful for slashing.

Of course it's not as effective as a cleaver or a cutlass, but the reason that Weiss gave it bladed edges is because it wouldn't be quite as useful for combat against monsters if literally all she could do with it is stab them and use Dust. If she runs out of Dust, all she has now is an oversized needle... unless she gives that needle the bladed edges of a normal sword. So, yes, it is useful for slashing. Not as useful as Blake's katana and cleaver, but still useful.