-Ophelia's right eye isn't exactly like a buff/debuff switch, but it is stated to be a jewel ranked mystic eye with the ability to cull any possibilities within a targeted existence and narrow events to a single course.
-Ironically, as she was supposed to be the one to save her lostbelt, the power of her mystic eye forced her to contact with the only possible outcome available when she laid eyes on her lostbelt, which was the fire demon Surtr. Thus, Surtr breaking out of his cage had become inevitable.
-Surtr's sword is also described as a 'god-killing armament', forged by the planet itself that takes absolute priority over living organisms with form or flesh. It's said that even the gods during the AOG wouldn't be able to withstand it.
-Valkyries are created by Odin himself, and the servant you can pull from the gacha are three of Odin's originals: Ortline, Hildr, and Thrud. They can have varying personalities, but none of them come into conflict with each other. They prefer to be seen as a colective consciousness than individual beings.
-They wield spears that are copies of Odin's gungnir, which has the property of never missing. Even if they're degraded copies, the posess an additional effect by producing a barrier that blesses the innocent and purges evil. Beings who posses magical energy and fail judgement will be annihilated. It's a B rank anti-army np.
-There's also a little tidbit that's dropped somewhere that after Bryn fell in love with Sigurd and was reduced to a human, the creation of Valkryies began to slow down. However, there are lines that say that there are potential active Valkryies that roam the world still in search of heroic souls.
-The Illya we see is a combination of three divine goddesses: Freya, Shitonai, and Louhi. However, the fact that this is Illya somehow allows her to summon Berserker Heracles to protect her. No doubt this is due to the connection they share.
-The fantasy tree in this lost belt is named 'Sombrero'. No, it's not named after the hat, despite what many people believe. The most likely answer is that it's named after a galaxy that's 31 million light years away. It's shaped like a sombrero, hence the name. Also, the last fantasy tree, Orochi, is also a galaxy as well despite being named after the legendary japanese monster. So, it wouldn't be farfetched to say that the future trees will be named after galaxies as well.
-The Wandering Sea is a akin to a portable reality marble that moves around randomly. It supposedly surfaces on the date December 31st only. Da Vinci says that the creation of such a territory can only be achieved in the modern era through the use of a Ploy-Kicksaw, an existence only made possible by the Inheritance of the Witches. Alice Kuonji in the future?