So where to begin? First off, it is a turtling weapon, which is helpful, however I found alternating inbetween turtling and just swing created a lot of openings from opponents. So I'd take a poke at them without blocking (which has better range too) once, jump away, and the next time they got close, I'd pull up my shield during my next poke, making their swing miss.
It does around 120-180 damage per hit, ironically, the less damage I did, the better, as I could stun the ones I did 120 damage to, since light armor has better magical defense. My biggest asset however when using a rapier is the running attack. This thing is beastly. Two attacks, doing 110% and 120% light attack damage... without loosing any momentum throughout the entire attack? I used this attack to chase a ton of flaskers, gankers-with-dead-phantom's, and just general dodgers, and it's hilariously effective, often pegging them with either the starting or ending blow, even with the ninja ring on. I even could keep pressure on Divine Blessing spammers, because the attack was fast enough to kill them before they get a blessing off.
Combined with how a rapier has a naturally higher backstab damage, I don't see why these beasts of weapons are not more used.
PS: And the Shotel is a pitiful weapon, as soon as someone pulls it out, I just press R2 and instantly get a parry, because of how predictable it's attack is.