Hey so I decided to whip up something really quickly to represent a few ideas I had for the health bar in the game. Keep in mind that all of these are VERY simple representations of what might end up being the completed design. I mainly wanted to throw out a few ideas and get some feedback before I went ahead and made colored and/or more complicated designs.
You can see that some of these designs deal with keeping the health bar on a physical object (such as a backpack) and some appear on a hologram-type object such as the shield or the swirling health bar. We can also toy with the idea represented in the gauntlet image where the physical object projects a holographic health circle and when the health is taken in game the light on the object turns off.
Anyway, let me know what ideas you would rather see and I'll go ahead and make a bunch of better-looking varieties of those designs.
Feel free to mix and match :)