Huh. That version of stone palm is... a bit weaker than I expected. Having to use a standard action to get it, and having to make saves to keep it if you become bloodied, both make it hard to use for a defender.
Really, all I'm trying to accomplish with Stone Palm is to have something roughly comparable in power to a shield, with cool flavoring appropriate to this setting. This version is much weaker.
Could we perhaps make it a stance instead, as a minor action, usable once per encounter, with duration as normal for stances (until the end of the encounter, or you become unconscious, or you take another stance)? That's still weaker than having a shield (because I had planned to take and use the Boundless Endurance stance, which I won't do if Stone Palm is a stance), but usable at least.