>>76312218Rate of force development, that's your body ability to produce force, aka power.
The speed of the move doesn't matter with rfd, in fact being faster makes it harder to produce power because you have less time to produce force.
With fedor i mentioned he lifted relatively heavy weights fast, if you lift anywhere from 60 to 90% of your 1rm and move it as fast as possible you will develop speed and power, if you lift lighter weights you will develop speed but no power because the force production isn't high, if you lift heavy weights fast but not as fast as you can, this produces more force development but not as much speed because you are close to your max force production (your 1 rm) but it doesn't develop as much speed because you are not trying to move as fast as possible.
This is called intent, if you try to move as fast as possible, you will get faster, if you try to move as fast as possible under heavy load near your max you develop speed and power, if you try to move as much force as possible fast but prioritizing force rather than speed, then you develop power but not much speed.
Now Arnie and liston weren't lifting weights during their time, this was as a general example, they mostly did calisthenics but applied the same concept, when you do high reps in calisthenics approaching failure you can still build muscle and strength, they did that but trying to apply as much force as possible and since they were approaching failure this made those last few reps felt like heavy weights which develop their power but not so much their speed.
Basically, fast but weak fighters move fast but don't generate enough force, fighters that are slow but hit hard generate force but don't try to move fast and fighters that have speed and power move fast and generate a lot of force.