This could be Runemarks, a 2007 novel by Joanne Harris.
The story follows a young girl who is ostracised by the others in her village due to her having a runemark on her left hand.
During the story she meets up with a one-eyed trader that she later discovers to be Odin and performs magic in the cellar of an inn to stop an influx of goblins. The synopsis from Wikipedia seems to match the points remembered in the question.
Runemarks follows Maddy, a young loner who has been ostracised from her town for the rust-coloured rune mark she carries on her left hand. Animals born with a rune mark on their bodies are seen as cursed or deformed and are usually quickly slaughtered. Maddy is allowed to live because she is human, but is always viewed with suspicion despite this. Her village does not follow the Norse Gods, as the puritanical regime known as the Order has mandated that no one is to speak or acknowledge any of the old ways, let alone use magic. It is only after she helps rid the local inn's cellar of goblins that Maddy discovers her latent magic, with it quickly becoming something that is occasionally useful to herself and those around her. As the book progresses Maddy flashes back to her childhood where she learned about runes and Norse legends through the old traveller One-Eye, who later reveals himself to Maddy as Odin and involves her in a quest to find a treasure buried beneath Red Horse Hill. As they search, they come across several other Norse gods and are led into a confrontation with the Order and their leader.
There is a sequel from 2011 called Runelight as well.
According to this link from Goodreads, Runemark as Feuervolk has been published in German and a number of other languages.
