Hmmm not really - consider none of the material on Belus was actually new.
Wrong. Varg has made clear on a number of occasions that the album is made up of both old and new material, though he didn't do into detail about what is new and what is old. "Glemselens Ev" surely is of newer vintage though.
Edit: Wow, apparently Varg at some point actually wrote down a timetable for the compositions. You can see it for yourself on the Burzum website for the Belus entry in the discography. Surely there are elements in some of these newer compositions that hold origins in earlier ideas, I would wager.
Title Production year (location)
Leukes Renkespill (Introduksjon) 2010 (Bergen)
Belus' Død 1993-1994 (Bergen)
Glemselens Elv 2008 (Tromsø)
Kaimadalthas' Nedstigning 2009 (Bø i Telemark)
Sverddans 1988-1989 (Bergen)
Keliohesten 2008 (Tromsø)
Morgenrøde 2009 (Bø i Telemark)
Belus' Tilbakekomst (Konklusjon) 2009 (Bø i Telemark)