I guess that is it.
Of course, it doesn't really matter from a pure gameplay perspective;
I just felt it was slightly awkward how the Knight was limited in a lot of ways like that, but I almost only use him for CURE and CUR2 spells anyway, and maybe FOG and RUSE a couple times, if physical defense becomes super-important and should be maximised as much as possible.
Actually I probably don't even really use the actual RUSE spell that much, since you get that spell for free in an infinite amount from the Defense sword, which is cool;
but I would probably give the Defense sword to someone who cannot normally use RUSE spells, at least once Knight has some better weapon to play around with
(such as the Sun sword or the Xcalber, or the Masmune of course).