TL;DR: PvE is predicting, PvP is being unpredictable

Research: There's usually an abundance of videos of people using any given weapon, so watch some of them and get an idea for how they use the weapon in PvP.

Moveset: Know your weapon's moveset, such that you already know what it will do (when and for how long you'll be vulnerable while you're doing it) with each type of attack, especially accounting for rolling/backstepping + attacking and one-handed versus two-handed differences. Get in the habit of swapping them up. This all becomes doubley as critical for heavy weapons where each attack is a major investment in time and stamina.

Offhand: Get an offhand weapon(s) that complement your greatsword like a buckler, a dagger, a rapier or a spell catalyst. Have a few, swap them sometimes. This is helpful because often people think they can get in close against bigger weapons because they'll see the attacks coming, and having a smaller weapon keeps them uncertain of which you'll use.

Locking: Some attacks - often jump attacks - benefit from locking, but we of the cult of gigantor slab weapons often fair better manually targetting so we can adjust our aim to be where they are going to be instead of where they are.

Baiting: Less about making them make a "mistake" as it is about setting them up so their in-the-moment decision benefits you.

For example, you're facing your opponent on a bridge. So you position yourself to the left side and feign an attack with a short animation. They roll forward on your right, except you already knew they would do this and you're already throwing a pancake manuever behind you right about where they are going to land.

Stamina: Standard PvP advice is make sure you have enough for a roll so you can get away.

But more than that, remember to visualize how much stamina your opponent has available. Keep track of how much stamina they expend before they retreat from a round, indicating they ran out. When they overextend themselves and you're still in the green you've created an opportunity to do some damage where they can't dance around.

Vigor: Look, you're not a sportscar, you're not even a minivan. You're a stripped down humvee with the anchor of a battleship mounted to the front of it on a chain. So do yourself a favor and have a lot of health so you can absorb a few hits to get in closer or get yourself into position for a good attack.

Crypt Blacksword represent. ^<3 u BB, ^u my grape popsicle.