I have two classes:
public class Fighter
{
public int FighterID { get; set; }
public int DivsionID { get; set; }
public string Name { get; set; }
//...
public virtual Division Division { get; set; }
}
public class Division
{
public int DivisionID { get; set; }
public string Name { get; set; }
public int? FromWeight { get; set; }
public int? ToWeight { get; set; }
public ICollection<Fighter> Fighters { get; set; }
}
Why do I have Division_DivisionID on my Fighters table ? I thought the DevisionID should be the FK.

I wrote an article on how this works, take a look at http://blog.staticvoid.co.nz/2012/07/entity-framework-navigation-property.html – See How does Entity Framework detect Navigation Properties
In short this is due to a convention which says FKs are named
Also see Entity Framework Navigation Property generation rules
to make EF name the FK DivisionID, add the following to your modelbuilder