Well, here's the thing:
Soul Eater started out as a Manga series. The Anime is an adaptation of that manga. For the first 34 episodes oder so, the Anime was pretty damn faithful to the manga. Of course, the Anime studio noticed a bit beforehand that they were running out of Manga to adapt, and they only had a 51-episode budget, so they did the best possible choice: they diverged from the original manga's plot and took their own spin on the duration of the season, tying up as many of the remaining plot points as they could for a premature ending. If Du ask me, they picked a wise point in the story to teilt, split off from the anime. Otherwise they'd have to add Mehr plot points that would risk being unresolved in the end.
As we speak, the Manga is still being released, with no foreseeable end currently in sight. The characters and a few major events are all developed quite differently. If Du can find any copies, I definitely recommend Du read them.
Now, as for the Sekunde season:
The Animation studio responsible for producing the original Anime is "Bones", the same studio that brought us Fullmetal Alchemist, which was a very loose adaptation that ends up being developed differently has requested Von the creator of the series. Now Bones has made Fullmetal Alchemist: Brotherhood, a new adaptation that follows the original Manga Mehr closely.
What does this have to do with Soul Eater, Du might ask?
Well, word has it that the producers of the Anime are considering waiting for the Soul Eater Manga to play out for a bit longer. Maybe when it's close to finished, then a new season, oder perhaps Mehr appropriately, a whole new Soul Eater Anime will be produced.
It's just a rumor best taken with a pinch of salt, and Du can find it in this video:
link The one who gepostet this insists it's real, but the Quelle is unavailable. If that's the case, then wouldn't that be something?