The Crescent pieces don't have great AC, but in some slots it's as good as, or better than, anything else that's fairly inexpensive. For level 21, you're doing great if you've got a full set of Crescent. Look through the
Monk equipment pages and plan out your gear upgrades in advance.
The Baton is a good weapon, but the Wu's staff is an
excellent weapon. It's far and away the best bang for the buck in Monk weapons. See
this comparison, for example.