Looking for a skirmish ruleset set in the crusades that would fit this Varangian

[Aethelwulf]

After hearing that the Byzantines had flamethrowers, I obviously had to have one. So I converted a viking into a Varangian guard with a flamethrower, but then I realised that I don't have a ruleset that would fit with him, any suggestions?

Here's the Varangian (Erak Flamespitter)

[Freddy]

Not sure if they had a handheld one, the one I saw was attached to a ship.
The skaven flamethrower rules might worth checking though, either in WHF or in KoW. Except that I would do this as a one shot weapon. The easiest would be dealing som fixed damage and a morale check with some really heavy minuses.

[Aethelwulf]

Here's a hand held version.

[Galtisant]

SAGA: Age of Crusades includes rules for troops like this.