This item heals the same amount as a Healing Potion, another common consumable.
- It can be used at range
- It can also miss (especially with high AC allies)
- Plus, the range is only 20 feet or disadvantage.
- If you use this on an unconscious ally, the target will be prone and you will have disadvantage unless you're in melee range
- If you use this on an unconscious ally, you have advantage if you're in melee range
In fact, since the brick also does damage (as I've realized from the OP's comments), a melee attack heals on average 2HP on an unconscious ally, and might leave him unconscious again as it crits for 2d4+STR damage. To be honest, I think the item doing damage as well as healing seems to make it useless. I would just leave it with the healing part. Doing damage, it feels like it's only worth it to use if you're a DEX character with multiple attacks, and even then only if there is someone nearby with an actual Healing Potion ready, if you happen to miss.
If you main concern is
being able to wake knocked out allies from afar, without exposing the user to danger.
then it shouldn't be a concern. When you use this brick, it is in fact the unconscious PCs that should be concerned with being exposed to danger. Your mobs now have less PCs to worry about and, if the conscious PCs are hiding behind pillars to heal their comrades without exposing themselves to danger, your mobs have the advantage anyway.