Ok, so the origin of this game mechanic is quite simple actually.

While I was working on update 2, Doom 2016 came out and everyone was hyped about it, including me.

Then I though, how possible would it be to implement some of these mechanics into csdmo, while keeping most of the code as intact as possible? as I didn't wanted to make a standalone project for such trivial idea.

Then, decided to experiment a bit with the weapon powerup mechanics, something that was implemented on both heretic and hexen.
The Idea is that you give the player a tome of power that that changes how weapons behave.
The changes are limited but with few tricks you can achieve some cool alternate behaviours.

That's how i've done centered weapons on Titan, multiplayer weapons on Q4 rip, alternate ammo pickups on Doosk, dual wield on Serious Doom, and Rip and tear mode on CSDMO.

My trick was to give player the tome of power (powerlevel2) if player chooses certain skill level, and make the powerup last for the whole level. That way, those tweaks last forever (I mean, it actually lasts for 4 years "0x7fffffd", but you wouldn't spent all that time on a single level just to prove the bug exists, right?)

The powerlevel2 is a cool feature that can lead to cool tricks, I just like to experiment with it and do different things on each mod.