Throw Stone's not really a combat move, it's a "Cure Charm/Confusion/Sleep from Range 4" move. Sometimes you can use it to shift your character one spot over to for some minor health but you probably want to save CT instead.

Squires used to have another niche move in Beatdown which was removed this version. This class really had it rough.

Unfortunately in FFT it's much better to do one thing very well as opposed to many things badly, as seen in Item which is a top tier skillset solely through the power of Phoenix Down. If you can take on extra roles while still having a strong corner on a market like the White Mage (has a niche in full-health revivals and can buff, nuke and heal when needed) then you're good but clearly the Squire isn't at that level.

It'll probably be more interesting to just give him one solid combat move and make him better at support - there's a solid germ of an idea in Wish, Cheer Up, Heal and Throw Stone, but their power level is currently too low.