While more can always be said, some posts found in these previous questions threads (answered by /u/Arilou_skiff, /u/vonadler, /u/Hergrim, and me) will still be of some use to you, I hope:

• Would post-viking era Scandinavian armies and soldiers be organized and equipped any differently than other "western" medieval armies?
• A Question Norse and medieval infantry and weapon/armour choice
• When did the Shield-wall strategy die?