That's missing "d", "g", "i", and "j", unless I'm missing something.

Just for fun, the JavaScript one-liner I used to check:

  const check = str => [...Array(26)].map((t, i) => String.fromCharCode("a".charCodeAt(0) + i)).filter(l => str.indexOf(l) < 0)

Yeah, I believe the line is “... judge my vow” for that reason. (Sphinx supplies the “I”)

And a mildly golfed true/false check:

    str => [...Array(26)].every((e, i) => str.indexOf(String.fromCharCode(97 + i)) >= 0)

There should probably be a .toLowerCase() in there, though.

If you have access to a keyboard, it might be easier to just run your fingers over it to get

    "qwertyuiopasdfghjklzxcvbnm".split("")

Dub waltz "Nymph", for quick jigs vex.