Legacy or Mecanim animation for changing equipment and skills

This is for a 3D game.

I have a system which allows me to take in different equipment such as a sword, Bow, 2-handed sword, Dual wielding swords, holding a sword and shield, Staff, etc.

Each weapon is different enough to require its own set of skills to simulate a different fighting style using the weapon. Each skill has its own animation unique to itself to be played, and blends in with the lower body animation if needed.

The player is able to sheath and unsheath weapons, and is able to change their skill loadouts for each weapon in a skills window.

So far this system uses Legacy Animation to run its animations and works great. What I am curious about is how this same thing might be done in Mecanim.

Feel free to ask questions to clarify details