New idea:
Manmelter
+5%movement speed when active
+30%dmgs
can store crits everytime you taunt
-25 max hp

Actually manmeltet is a very situational item becoz no knockback and can store crits only against pyro bosses
so it needs another way to store crits.

Mantreads still do nothing except the usuall TF2 Things.
It should knock you back like Flare Jumping, but also hurt you like it.
Maybe, no fall dmg?

https://wiki.teamfortress.com/wiki/Freak_Fortress_2

"Air Strike gets its clip size increased every 200 damage."

What about giving soldiers with mantreads the ability to weight down?
Not instant-weight, but like vanilla hale weight down?

https://wiki.teamfortress.com/wiki/Freak_Fortress_2

"Mantreads increase the height of rocket jumps, and also reduces fall damage in place of its normal stats."

This buff is already on this server but it doesen't work.
But in other servers it got fixed.