This mod is simple: it alters how invincibility frames behave to make weapons with more than 2 attack speed more useful.
How it works:
Normally, you can blow a maximum of two hits per second on a mob due to invincibility frames. However, with this mod installed, the higher your attack speed is, the shorther the i-frames become. The lenght of the i-frames depends on your attack speed. For example, with 1 attack speed the i-frames stay the same and you still can land only 2 hits a second at max, but with 5 attack speed the i-frames get shorter, letting you hit the target 5 times a second.
The mod has some configs too, they are located in serverconfig folder of your world's folder.
You are allowed to use this mod in your modpack.