Errrr...Hermod's Ride To Hel does not have a solo...maybe in your dictionary it does, but not mine.
Anywho the songs that actually have solos (you know, fast guitaring on the higher pitched strings, often past fret 10) are Valhall Awaits Me, Asator, Gods Of War Arise and Under The Northern Star.
Anyway out of them it's a tie between Asator and Under The Northern Star, they both fucking sound great.
I don't know what song, but one of the solos has the same melody as Under the Greyclouded Winter Sky (only for four notes or so), so I guess I'll go with that one.