The Dragon Heart will be given to after taking on a couple of missions in the game and you will soon find out that it’s an important tool in battle. The Dragon Heart allows you to quickly heal yourself by pressing the LB/L1/Q button.
You want more heals with the Dragon Heart? You can upgrade it, but you’re going to have to rescue an NPC and bring them back to Ward 13. This half human half root creature will upgrade the Dragon Heart after you’ve freed her during one of the story missions.
Once you’ve set them free and held off a root attack she will spawn in the west end of Ward 13 under a canopy near the other vendors. The upgrades will require that you have Simulacrum and Lumenite Crystals. Simulacrum will only be found rarely in the game usually by killing powerful enemies, while Lumenite will be somewhat common in chests and enemy drops.