Gotcha Mike, but being a notorious fatty (215# when in shape) I always worry about rapping on skinny lines and them getting cut. Throw in (the case of the OP) the possibility of rapping on iced up lines and I guess my nut sack just shrivels at the thought.
Pretty sure people have been rapping on "spectra cord" or the like for a long time, but I thought handling issues and limited utility (ie cannot double as a lead line) had precluded their use? I guess if you are soloing some route and only need it to rap its a thing?
What the hell do I know about Alpine anyways of course (shudders at the thought).
I think that a munter hitch would work, and I have very serious doubts about almost everything else. Some years ago I wanted to descend a fixed line (perhaps 6 mm) to the Hollow Flake, and the munter worked like a charm.
Another time I attempted a rappel on a 9 mm line and used what I thought would be an ample or excessive number of carabiner brakes. (I had used carabiner brake systems for many years, and most typically there was so much friction that I had to force the rope through.) I don't know if there was some adverse combination of carabiner sizes and shapes, and/or a surprise regarding the rope finish, and/or my misperception of the rock angle, but I could barely control my rappel.