I am in the mood for rambling about this lol. I posted and rambled a bit already on my tumblr but I wanna ramble more. So I will do so here as I have no one to ramble about this with and if I don't let this out I will be even sadder ><;
Rather than normal crossover, this is more of my experience and talk with other fans in regards to zektbach characters. Matin is by far the one with the most often being thought as other character, which in this case is Gwendolyn from Odin Sphere. This can be just from looking the artwork itself and when I actually cosplayed Matin. I think the outfit especially the black bodice confused people, then the hair accessories. Even though Matin dahlia is different to the feather accessories worn by Gwendolyn in her gown version, the feather flower she wears in her distinctive valkyrie form is indeed similar as it has same blue colour.
Hannes in her default nun outfit is not mistaken with Saber from Fate series. But many fans seems to connect how similar they are, especially Hannes's hairstyle is basically identical with saber except for longer front hair. Mishie told me as well that she got mistaken for Saber when cosplaying Hannes in her empress outfit lol.