Karin, this polish is very little abrasive but with some care you can use it without damage the crossgrain. I'm now just polishing my new NSKK dagger with it and I'll post results here soon.
Yes, after polished Renwax leaves a vitrifyed layer on blade, but it's necessary to protect blade against humidity. If you need to remove Renwax, I think the polish can made it without risk to crossgrain. I think you don't have very much difficulties to obtain Renwax, it's made in England.
This type of F.W.H�ller MM is frequently used in Luft and Heer daggers, I never had see it on SA blades.
It's my 2nd Luft F.W.H�ller, the same on my avatar.
