After five years, you'll be fully 'vested' in the company pension plan. [=you will have earned the right to get a full pension when you retire]
Congress is 'vested' with the power to declare war. = The power to declare war is 'vested' in Congress.
She has a 'vested interest' in seeing the business sold, as she'll make a profit from the sale.
(..) CP. Shots fired on five. Repeat: Shots fired on five. Sergeant Tate. - Holy shit. - What the hell...? Shut up. Bobby, get the vest. - Right, sarge. - Brady, Howard, cover... Look! - It's stopped. - Seal off a ten-block radius. (..)1991 The Silence of the Lambs