Try the skill level "3 - Normal".
There you will find many new weapons
where they originally Doom spawn in the map:
BurningBarrel - EvilEye - Infrared - Berserk
When obtaining weapons in these Skill Level,
StellarWeapons will remember all your previous progress
and will suggest if you want to recover the weapons
and ammo upgrades
that you found
in other game sessions.
also, In the current version 8.0, (Please, Check this in the STARTUP Logo)
there is a orange difficulty called "6 - Online" where it is more easier to find all weapons in the Mod.
But, weapons will not be saved for other game sessions.
Basically like in any other Mod.