ZDoom

Should be better now. Let's hope that I didn 't miss some other edge case.

Fortunately Dehacked never had access to the ready sound property, so I think what can be done is to let Dehacked clear it for all weapons it touched that do not link to the S_SAW state.
I'm a bit surprised this never came up before - the bug had been there for all eternity - it got added in the early 1.23 versions some 20 years ago.
Apparently it is exceedingly rare for Dehacked patches to remap the states for disabling this sound...

The problem from what I can tell is that zdoom plays a weapons ReadySound whenever A_WeaponReady is called on the state right under the Ready label, but vanilla only plays the chainsaw idle sound when its called on the state S_SAW and the current weapon is the chainsaw. The axe in Vesper explicitly doesn't use the state S_SAW to avoid playing the sound at all.

This seems like it's going to be tricky to work around.

Not sure if that helps, but the Vesper DECOHack source is available at https://github.com/XaserAcheron/vesper.

From that it should be possible to create a Dehacked patch that only contains the axe.

I have to admit that I have no idea how to debug this. All I have for reference is the Dehacked file which gives me zero clues what to look for.
This will be an ongoing problem with MBF21 - unlike DECORATE or ZScript the 'code' is way too messy.

Same as viewtopic.php?f=2&t=75535 , most likely.

Exactly what it says on the tin. While in its ready state, the vanilla chainsaw idle sound plays repeatedly. This isn't supposed to happen.