That arrow could be a decal. You could rotate the object and it would still project onto it but you would have to keep the decal location updated which Im sure you could do with blueprint.
Maybe this might help UDK - DX11 tessellation/displacement icicle material tutorial - YouTube
That video shows you how to set up a material that is only applied in a certain direction and the texture moves with the object. The video is for UDK but the same can be done in ue4