Nicknames beginning with '-' are not valid nicknames
Good point. I am guessing that BNCs use non-valid nicknames so that they don't collide with nicknames on the IRC server. So the issue with /msg and -switches support will likely only be an issue with users who use certain BNCs. Does that make sense?
Also, /describe and /notice work in the above case only because no one has ever asked for a -switchable feature for them. If someone did, and it was added, they would have the same issue.