Well, I was thinking of an Idea. What if Jack was using chains as a special attack. I mean attacks like whipping your enemies and it can also be used for grappling platforms much like Link's hookshot.
When I am talking about special attacks, you are probably thinking it costs mana or magic. But I decided it would be unique for the special attacks to cost his own HP. Well, that is because his chains are made out of blood. Yes, his special attacks are made out of his blood. But don't worry, your HP heals little by little over time since Jack is a homunculus with an increased regenerative algorithm.
For his projectile attacks, I am guessing he launches something like a bloodball (Like Mario's fireball) or maybe blood spear.
Idk, if you know a better idea please leave in comments below