Note to self. Using mysqldump to dump a table with latin1 encoding and then editing it and importing it into a second DB with utf8 encoding isn't a lot of fun.
I found some instructions for properly opening mysqldump files in Vim with the proper encoding. I'm still somewhat confused what the difference between enc and fenc is in Vim but this worked. Eventually.
Also during the hour of banging my head on my keyboard, somewhere I read that using shell redirects to dump the mysqldump output to a file is sometimes a bad idea if there are multibyte characters in it, and instead you should use the -r flag to specify an output file. Could be true, I don't remember.