I'm a little torn on this one, because it's hard to not just make it The Even More Direct Hit.

Hell's Heart:

>Harpoons fire with an arched trajectory
> Alt fire: hold to launch a special harpoon that pulls you to where it lands. If this harpoon hits a player, it instead pulls them to you.

+ 50% faster projectile speed
+ 30% damage bonus
+ Harpoons push players back on impact

- Harpoons do not explode


Not sure how well this'd work, but it's the best I could think of. A wacky fusion of the Direct Hit and Loose Cannon. The primary gimmick would be the alt-fire grapple hook, which would act as a replacement for rocket jumping. That, and you could try yanking someone to you then skewering them.

The harpoons clearly have a rocket in them, a re-skinned direct hit would do

It could be neat if when you pulled someone, it would deal bleed.(Yeah, that's really obvious stat but still).

Those are really good stats, but it does have a rocket. Then again I agree it shouldn't explode

Hell's Heart
Level ??? Harpoon Launcher

Neutral
Rockets arc downwards

Pros
On hit: Bleed for 4 seconds
+20% projectile speed
+10% faster firing speed
+2 health regenerated per second on wearer

Cons
-85% explosion radius
10% fire damage vulnerability on wearer

(I was thinking of a weapon that would pair well with the conch.)

+/- underwater and above-water projectile speeds are swapped, and made more extreme
+on hit: instigates a bleed affect
+ +150% wearer swimming speed while active
-projectiles do not explode

Little bit of a modification of @Stogie's idea, in an unorganized layout

Left click: Hold to charge a harpoon. Longer you charge, further the harpoon goes.
~Base harpoon does 30 maximum fall-off and 115 maximum ramp up
~Travels at 900 HMPS (hammer units per second) at minimal charge and 1350 HMPS maximum charge
Right Click: Similar to the Cow Mangler, slow down your speed to charge and launch a special harpoon with a rope attached. When the harpoon lands, the user gets pulled towards the landing point. If it lands on an opponent(s), it will penetrate and deal bleed damage. Recharges 7 seconds after landing. Can be canceled anytime during being flung by clicking right click again.

~Normal harpoons penetrates through opponent, but deals less damage the more enemies it goes through. Deals no bleed damage however. (doesnt make sense but this has to be balanced somehow)
-No splash damage/ -100% explosion radius
-No rocket jumping
-"""rockets""" affected by gravity
Hidden "stat": +Special Harpoon allows you to "nullify" pyro airblast (You still get airblasted but the rope still pulls you)
Hidden stat: projectiles fired by this weapon count as bullet damage rather than explosion damage
+2 clip size
+10 carried ammo (what the tfwiki calls it anyway)

Stickbomb launcher if it fired spears instead of stickies. Mostly gimmick-y but fun(ny) sidegrade to the stock rocket launcher. The loss of all spash damage in order to fly around the map and deal bleed damage is a heavy loss, and would need readjusting to from the usual soldier playstyle.

Originally posted by Lovecraft Gaming:

The harpoons clearly have a rocket in them, a re-skinned direct hit would do

Agreed; The only stats I can think of are gimmicky underwater weapons. Besides, it's not like Soldier has a shortage of weapons :P

Hell's Heart
Level: 1851 Harpoon gun

= Rockets replaced with an heavy harpoon projectile.
+ Holding primary fire launches the Harpoon farther.
+ On hit: one target at a time is marked for death, causing all damage taken to be mini-crits for 5 seconds and slowed for 10 seconds
+ Deals 15% more damage.
- Has 70% smaller splash damage radius.
- 75% Smaller Clip size

+/- fires a high speed blade projectile
+bleed on hit
+crits when it would mini
+10% faster reload
-no random crits
-one shot

Concept: Not a rocket launcher, but a weapon designed to impail and capture targets. Best paired with a shotgun for a quick combo.

Pros:
On hit: impails target, reducing their movement speed by 90%
On Alt-fire: reels in target launching them towards you.
No damage falloff

Cons:
projectile affected by gravity
no splash damage
no knockback
Projectile must stay in line of sight to hook target.
Switching weapons will unhook targets.