Ok so I've got the source code for the "unofficial 1.4.0" release posted by Oblique in #459. I'm not going to roll it into the main branch yet though, because I've got some ideas for improvements, which will all be rolled into 1.5.0.
Spy viewmodels can now be properly hidden
I finally figured out how the off-hand (watch slot) weapons work. They used v_models the whole time, they never switched to the c_model system. You can now disable/enable these for each *weapon*. You could choose to hide the Quackenbirdt, but keep the Invis Watch visible, despite the fact that it might seem like they're the same animations.
Full support for custom animations
I'm going to change the editing process so that each weapon will allow you to use a custom animation instead. I'll try to work with Paysus on this. You'll need to request custom animations, they'll be bundled with the installer.
More flexibility in how things are hidden
I'm going to look into weapon offsets so you can move the viewmodel rather than just hiding it. This will take some experimentation, please bear with me. Probably won't make it into 1.5.0.