Editing Animations

hi, i made my game in the third person example map, and made it first person, but i need to make the arms in front of the camera like in a first person and make them not move, except for when he swings(has a sword).
How do i do this? i cant add keyframes to a custom animation i mean seriously wtf epic games “Hey lets, let them be able to make animations but letss make it so it doesnt work!”