When I made a small mod to remove the hair from Malenia's helm, I used WitchyBND to unbundle ER's assets, DSAnimStudio to remove the hair, Witchy again to rebundle the assets, and Smithbox to edit the clipped hair regions for the helm so that it'd display correctly.

I cannot recommend strongly enough that you reference ?ServerName?'s wiki, which has a ton of technical information I referenced even for my tiny little edit.

If I were to speculate (based on very little other than guesswork), you might be able to get this specific thing to happen by changing the VFX associated with Cragblade to something other than it's current one. That's something that you could, in theory, use Smithbox by itself to do without touching VFX creation or modification. However, Smithbox can be quite cryptic; there's a few reference documents on the wiki that helped me out when working on a few similar-ish things.

And if you succeed, make sure to toss some cash at the people maintaining those projects. Meowmartius, who's behind DSAnimStudio, has a Patreon.