ZDoom

Remember: Even then this needs to be done 4 times...

Figured as much. But perhaps add it to the list of "maybe someday"?

Easier said than done.
We are talking of code with a considerably different quality here...

Currently it's not generally possible to use the next/previous weapon keys to quickly scroll to the weapon I want to use, because the games generally don't allow changing to the next weapon before the whole weapon lowering/raising hassle has finished.

Maybe implement a system similar to ZDoom to make quick weapon scrolling possible? I also kinda like what they did with Blood: Fresh Supply. Very illustrative.