Just copy and improve. If it works for your playstyle, use it.
I don't think I've developed any sort of "tricks" or attack-patterns by myself. I've learnt by watching the masters and legends of the past and improved upon their legacy.
TheNarrator - The creator of the spinthrust. I tried to copy his style, took me 2 weeks before I started to get the hang of it. His spinthrust was kind of basic, vertical downwards. I spent a month of just perfecting it and taking it to the extreme, side spinthrust, ground and upwards spinthrust, all the variants. Took a good 2-4 weeks before Kekn, Hubbel, Weirdo and the old school Ndition duellers figured it down and started doing it themselves. Kekn took it even further then me, his spinthrusts were the most retarded I've ever seen.
Ereev - Chambering. Nothing special, took me half a year to master it, but if you add feints and/or holded attacks after your chamber it can be used to even more deadly effect. Most of the "pros" around here still fall for a holded chamber attack(Including me, most of the time). Ereev was special, he could chamber holded attacks, somehow... still trying to figure out how he did it...
duckduckMOO - Feinting rotations - duckduckMOO, this guy was insane and it took me months and months before I reached his level of skill. He had it all, perfect blocking, footwork, chambering, but above all else, he had his feint rotations. By mixing left-slash feints with thrust feints, utilising the natural right-hand mouse movements, he did some really fast feints. I copied it all and I'm still using it.
Flash - Distance control - You know the drill. Side slash -> backpeddle -> do a thrust and fall back in on your opponent and hit him just after he missed you. Flash was the grandmaster of this. Copied it and with the current 2h thrust nerf, this type of attack works best of all.
Szymczak - Hiltslashing - Man, I was furious when Szymczak started utilising this a long time ago. He broke the sacred duelling rythm, attack block attack block. He managed to do an attack attack. I refused to use the same technique he did, I thought at the time that the duels turned into a strafe and spam contest, and it did at one time. However, after many duels I found the weakness and exploited it. After that my thought on the subject softened enough for me to copy it aswell, it's after all a very quick way to dispatch new players.
Morii - Feints with Hold attacks - Very basic but extremly deadly. Do fast feints and suddenly do a holded attack, time it perfectly and it'll hit your opponent since most people click-block. Copied.
I'm 99% certain that everything that can be done has been done. Engine and animation limitations has reached its peak of what is doable. All you can do is copy others and adjust it to your playstyle.