I switched from my Warder Bushi do to it not fitting the theme of the game i'll be in
so I am planning a Angel Blooded (lost promise) Aasimar
FiendBound warder and i could use feat advice
I want to focus a lot on grappling with my Fiends grip
and for Disciplines I plan to go in to Black Seraph & cursed razor
So i want to pick up either Black Seraph Style or cursed razor Style
but unsure what one will work better.
Any good feats i should take for this character?
You probably want the grabbing style feat line then. Keeping a hand free while grappling may well be useful. Improved, Greater and Rapid Grapple are on your to get list of course. Beyond that body shield and claw wrench are grappling feats you might look at, or you might look at feats related to your warder class features - extra readied maneuver and the ones which mention armiger's mark like guard's glare.
Going with Black Seraph Style would fit nicely with the Guard's Glare feat, forcing creatures scared of you to save if they even want to try and run away.
Cursed Razor is generally better for classes that get a Claim feature, due to feat synergy. Eternal Guardian (and EG Style) might be better for you, since it synergizes nicely with combat maneuvers and intimidation, while still getting all those sweet curse abilities.