Change letters for day name

In the comments, @vancoder points out that it appears day names are not capitalized in Norwegian. If you require that they be capitalized, you could do something like this:

ucfirst( get_the_date( 'l', $post ) ) . 
get_the_date( ' d.m.Y', $post ) . 
get_the_time( ' H:i', $post );

…using PHP’s ucfirst() to force the first character to be uppercased.

(I’ve also split the date and time to use get_the_date() and get_the_time(), since it seemed semantically cleaner to me that way.)