All three are tied to Opportunities
Impalement -
No Absolution for the Wicked Once you arrive at the top of the church you simply need to push him onto the steeple when he leans on the rail.
Pen -
Above the LawOnce you have arrived in your office, Abiatti will tell his guards to leave, then he will turn his back to you and lean on the desk, walk up behind him and press
to push his head down onto the pen.
Fireworks -
Dynamite SmileFollow the Opportunity until your bring Abiatti to the dock, when he begins posing for the camera, pull RT to set off the fireworks and eliminate him. (The guards might attack you after you set them off but as long as Abiatti dies, it will count towards the achievement)