I have a martial arts Harrowed. Does real well with his fists. With Soul Eater he can even do some magic damage. Has a coup that gives him Burrow to deal with ranged. I like having an answer to every enemy question. But against a tank, or anything else that requires heavy weapons, he's a target dummy. I was curious if anyone knew of an advance that would give hand to hand ability to deal some heavy weapons damage. Might be able to get around it with some monsters, attacking their soul with Soul Eater, but it's not going to work against a tank.
No, having double checked the Hell on Earth and Savage Worlds core rulebooks, I am not aware of any Edges or Powers that would grant an unarmed combatant with Heavy Weapons damage.
If this is something you want to pursue I can see two options, both of which enter the realm of house rules. The first would be to design a custom Edge that grants Heavy Weapons damage in cooperation with your GM, making sure the level and skill requirements are both appropriate. The second would work if you have a magic user in your party with an Arcane Background that would fit thematically with a power that grants Heavy Weapons damage. Again, this would need to be a custom house rule.