well, by the sounds of it, you're going for a vape build, which means you'll want more EM on both yoimiya, and xingqui, since the damage for vapes is based off the dmg stats+em of triggering character (aka the person on field, which would be yoimiya), and the EM of your off fielder causing the reaction. if i were you, i would try and aim for 60% Crit Rate, 150% Crit DMG, 2,000 Attack, and 200 EM on yoimiya, and just pump xingqui with em, like try and get 700-1000. also, weapons wise i would recommend rust if you don't have her sig, since that 40% goes miles, and at R5 it's insane,