Iolithe's page

Strength is kind of required given they didn't get a class feature to reduce the strength requirement of heavy armour.

That's true, but medium armor is also supported by many of the feats and could be viable.

As for initial feedback, I am curious why strength was chosen as the only key attribute. Would either con or a choice between strength and con would good here?

The Reaction Time feature seems a little odd. I assume that the intention is to give 1 free extra Reaction to use each combat (possibly tuned down from 1 extra per round), but per the rules in Player Core, you lose unused Reactions at the start of your turn so as written this ability can't be used. It probably needs a stipulation that you don't lose the bonus Reaction round-to-round until used.

I would say the intention is actually to give you a reaction before you otherwise would be able to. Normally in combat you only get your reaction on your turn, meaning the first round of combat you wouldn't have one until your turn comes up, but the guardian starts with a reaction always that allows them to defend someone round one.