I want to say that we shouldn't introduce new UI elements for the sake of a single weapon. The "bars" you speak of could exist but simply be invisible to the player.

Additionally, due to ping issues with other players, a healing projectile is significantly less helpful than, say, an area of effect. Perhaps we could introduce a new mechanic to the projectile that, upon hitting a target or expiring (after X amount of tiles or hitting an enemy, wall, etc) it creates a small explosion that heals teammates and knocks back monsters, dealing the current damage value of the projectile. Think of it like the "stay close!" mender ability.

Additionally, I would say the "healing circle" should only heal a few hearts even at maximum charge. I would say it heals as many pips as the star level at maximum power, and half it between the 5 to 9 period, making the 0-4 hits heal nothing. This means a 5* wand would heal 2.5 pips at 5-9 hits, and 5 pips at 10 hits.

The reset after so long is good, means you can only use it in combat. Respawning enemies already can be abused for heart attack so this is no different there, however it is something to consider when it comes to balance.

Another thing that might be interesting would be if getting hit applied the current heal you have stored to yourself, but negated the charge.