You can set the resolution and full screen mode manually.
Go to c:\Users\<username>\Documents\BattleForge\ and open the config.xml using a text editor (e.g. notepad).
Search for the word "fullscreen" (without he quotation marks) and set its value to 1
Next or below it (depending on the text editor you're using) are screenheight and screenwidth. Type in the desired resolution e.g.:
fullscreen="1" screenheight="1080" screenwidth="1920"