Following the 30% nade nerf i immediately began testing all possible options to maximize my dps again. i had the same question as you and after playing round with p/p AND p/s ive discovered that only 1 sigil work with kits at any given time. for rifles its obviously the one you have on rifles but for p/p and p/s it is the one you have on the OFFHAND that works with kits. so it doesnt matter what you put into your mainhand wep when using kits.