He is the current Pirate King... His bounty is currently unknown, but would indefinitely be higher than even Doflamingo's. The reason he does not have a bounty is because Freyja is the new Fleet Admiral of the Marines, after Sengoku's defeat. Anyone who knows Loki would know that even if he tries to trick people (Like the norse god I named him after), he wouldn't attack his sister. Not out of love, just because his sister has an ability (it is implied about her Devil Fruit) that would easily crush his own. Therefore Loki poses no threat to the Government. He even tried to prevent the Ouka Shichibukai Rebellion!
Loki's DF is the Reza Reza no Mi, a Paramecia that allows the user to fire lasers. These lasers are just normal heat, but they can be superheated or darkened for different combat effects. "Reza" is the japanese way to pronounce the english word laser.