I don't quite remember how I felt writing my first action sequence, some things just naturally come and go.
I can't say I have any top advice either, just envision the scene like you're watching a movie but pick out the most impactful movements and condense them into an easily readable sentence.
Don't add sound effects on a plain line like:
I'd personally go for something more along the lines of:
The air reverberated with a loud clang as their blades met.
Weapons bouncing of each other in seamless slashes
But at the end of the day it's up to the writer and their style.