WeaponCore is the mod framework for Space Engineers that makes StarCore possible.
What is WeaponCore?
Weapon Core is a complete rewrite of Space Engineers combat system. The way combat works in this system is very different from Vanilla and many conventions that you are familiar with will be different.
This "mod" by itself does not add new weapons to the game, it is the framework (engine) by which other weapon mod authors may create pretty much any kind of weapon they can imagine.