We've got Dual Dakra, Proto Excalibur, Proto Glaive, and returning from last year, the Dex Furis. Log in before April 1st or else you'll have to wait till next year!
It should be noted that the proto skins are just skins and are not given out for free, just the Dakra and Furis weapons.
The Dual dakra and Dex Furis both come with Catalysts pre-installed and a free weapon slot for each of them as well.