Ok, this is a bit shameful for me to recognize as more-or-less-fire-main, but...
I got Charlemagne weapon for fire, and I just can't find the way to make her shine over Shingen. Some ideas on how to use Charlemagne on fire?
My fire SSR are
Svarog Aw, Fire Frey, Uriel Aw, Fire Artemis, Maid Amon, Fire Sol, Mars, Ares Aw, Fire Mammon, Sonshaku/Sheren, Dakki, Acala (not Aw), Amaterasu, Yamaraja and Ra.