I'm actually having a mixed feeling about Shingen's Relic Weapon. Since my main is WATER, going for "Celestial Sailor Spear", which 1st skill gives a good Extra Large ATK bonus, isn't really effective since its 2nd skill was exclusively made for FIRE team (+35% Fire ATK). As for "Musou God Bow", the minus point is it's HP focused, though the colossal best point comes from the fact of increasing burst damage +500% with her Strike Forest instead of +200%. I'm actually leaning on the latter Relic Weapon despite the absence of ATK bonus since from what I can tell, that +500% bonus burst damage added to the standard 500% burst of SSR Kami, making it a good 1000%, x2 burst power and over millions of burst streak damage is just quite PHENOMENAL. Of course that's just pure theory, not sure about the exact damage formula, furthermore the JP wiki is still labelling it as (500%?) so I might just be too delusional.