In the krarc.protocol file it's stated that krarc supports some types of files, although the list is not complete. For example, it supports .7z files.

Note: krarc is supposed to open filetypes like .arj or .lha, although they are practically unused.

krarc can also open .deb and .rpm files, it's not the most usual thing, but if someone thinks that those types have to be added to the list, everything can be talked about :-)