Question about Legendary Engrams.

How am I able to raise the Power Level of the Engrams? I currently have a 280 Chest Piece (The Dragon's Shadow) and a 275 Auto Rifle (Hard Light) equipped.

However when I get the Legendary and Rare engrams from either Public Events or Strike Missons they are always decrypting at Power Level 268. Is there some way I am able to change that? Even if it's just raising it to 270.

I'd glady appreciate the help, thank you.