Films have three powerful tools to build a character: acting, monologue and dialogue. If they wanted to show that Vader is an angry person, they could have easily done it through those tools. Yet they did not (or completely failed to do so in case they intended), since Vader in OT is a very calm character with extreme composure. For example, when Vader’s TIE was rammed, they could have used acting for him to punch the joystick, or monologue to say something in anger, yet he calmly flies away. Another example, they could have made Vader’s reaction to Motti impulsive, rather than slow, clam and witty.
How is this (slamming his lightsaber furiously) calm?
https://youtu.be/GueBXRYVhe0
Pointless “slamming” (i.e., intentionally missing) is obviously part of Vader toying with Luke. When Luke cuts Vader’s arm, his sword style changes dramatically and Luke is elegantly disarmed in a couple of seconds.
Also you don’t get anymore blatant then “Much anger in him… like his father.”
Since you seem to like to use PT as a reference, you can use it here as well. PT showed that Yoda was often wrong. This can be another instance for you.