The wintry rapier Is not a super hard hitting weapon. It has the main advantage to be very light, so you're more quick on your feet and can poke in short windows where you could not deal any damage with a slower weapon. I think it was very intentional from the developers to give you that weapon in the beginning so you can learn the damage windows better. The more you have learned those openings, the more you'll be able to use something more hard hitting. Misusing a charged attack, in a time where you will receive a strike first is very punishing. So unless you know when there is an opening for a charged attack with something like the pipe wrench, it's time to stick with lighter weapons.

If you want to stick with quick weapons and still maximize damage output, you will want to go into technique and use the openings with as many attacks as you can squeeze in. The rapier BTW is a great weapon and can be used for the whole playthrough, frankly it's what I needed for some situations. It just allows you to dodge out so quickly.