Your translation shows your complete understanding of the phrase even if you do not like it yourself.
A difficulty this relative clause could present for the translator is the fact that 「霞む」 is an intransitive verb and that is not the action either performed by or against 「打突」, the main noun of the relative clause.
What I often do in such cases is that I rephrase it the way it does not change the meaning or nuance of the original.
I mentally rephrased this to:
The phrase became somewhat easier to translate and I now have:
"a strike so rapid that even its afterimage gets blurred"
A noun phrase needs to stay as such till the end. I said that because many users here tend to call a phrase like this a "sentence".