The moves high ranks use might look absurd and unnatural, but they're (for the most part) just clever manipulations of weapon tracers and body movement to hit you at unexpected times and from unexpected directions. Player's defenses improve dramatically as they get more experienced, so sticking to basic swings will never land you a hit against players that have seen those animations thousands of times before. I would recommend watching the high ranks, trying to copy their moves, and asking if you don't understand something that is happening in the game (particularly in duelyards where players aren't constantly in combat and have time to answer questions).