Crimson Grave
Summary
Many ages ago, a devil roamed the world. Bearing wings of black and eyes of molten gold, he traversed the world leaving a wake of death with his powers of glittering darkness. The Devil was slain by the 10 gods who created the world and to protect the world from further evil, the gods created 10 swords infused with their power....
Mirim is a member of the Ten Pillar Swords Guild. In fact, she is one of its top ranking members earning the title of "Crimson" and the right to wield one of the 10 swords forged by the gods. Her companion, Ash Grave, happens to be the devil of legend. Why is a swordswoman with a sword forged to protect the world teamed up with a demon seeking to destroy it? Perhaps there is more to this legend than meets the eye....
... and the second season of the Anime did a better job of pacing than I thought they would. I think they moved the Elf village arc from before hostilities with the Principality began to the inter-war period, aka the start of the second season, and used that to pad it out. Good call if that's what they did. In any event. Good season.