yes the claymore is a great PvP weapon. also, respect. a true souls OG. love to see it.
for PvE you have much, MUCH better options. but of course always go with what feels the smoothest/funnest to you because literally any weapon can beat the entire game. just some will do it much more effectively.
for example, you could go get the Milady and the ash of war that's literally meant specifically for Milady, the Wing Stance. this combo is incredible and really fun, and Milady is actually a decent quality candidate too. you can also just run it pure str or pure dex and it'll perform essentially the same
pair rellana's cameo with shard of alexander and watch everything melt in front of you. can also throw in spear talisman and a scorpion charm like lightning or holy if you have a way to consistently apply greases or buff incants if you respec.
another amazing PvP weapon, if you like dex playstyle, is the backhand blade found in the scorched ruins literally right at the beginning of the DLC. this is a grease/damage incant machine. it attacks lightning fast and suffers no status reduction from dual wielding unlike many other weapons.
if you like big bonks, the bloodfiends arm is found in the prospect town which is also in the very beginning area of the DLC. this thing turns anything it touches into a fine red mist.
any questions, feel free to ask. i love talking about this game