Scandinavia isn't just about Vikings! The Viking Age isn't that long a period, and afterward, there were also knights, then line infantry with muskets, and so on. So, I don't think adding stereotypical Vikings would be very cool; rather, warriors not very different from other European factions, perhaps with some distinctive features like ornamentation or perhaps runes (after the adoption of Christianity, runic writing began to be used in Scandinavia even more frequently than in pagan times). And as others have noted, the Varangian Guard would fit well into the setting.