When you see a power fist you just run and hope the guy with that fist is not following you. And you dont stop because you are gonna get sent back to your planet. Dead
Are you sure it wasn't an evade attack? They're light attacks but clang with Dbashes instead of getting stunned.
After a certain point in animations, the RPS system doesn't take effect. You can notice after a particular point in a power attack (mid swing), you won't be interrupted with light attack. Your attack will go straight through. The same applies to a limited extent with light attacks. The issue gets exacerbated with latency and people not using lock-on, so what appears to be the end of an animation may actually on their side be a lagged sword clipping you from the side. PF just doesn't work with the RPS system. RPS was designed around Powerswords, Chainswords, and Knives. Anything slower is inferior unless there's a mechanic that makes it broken in some weird, almost-impossible-to-balance way.
I think, he sure, who this was fast attack. After watch my own replays, i noticed one pattern, and check it in arena. I was right, fist after 1.3.11 can ignor Dbash in 100% of cases, if you know how it works.
Oh I've done it too, I just don't know what triggers it. I have noticed side stepping around someone while the swing animation winds up can result in funkiness too.