File:

meshes\actors\character\animations\aohammerwallloop.hkx

Here converted to "readable" xml for investigation, both vanilla and sialivi versions.

There's some kind of "address pointer" modified at lines 334 and 335.
I also noticed some changes in the 6 sounds that are called from line 835.
Other changes (if any) didn't catch my eyes...

As designed in this way, it looks like the called sounds are predetermined and not depending on the hit material.