Make the character an inventor/engineer and suddenly you have endless possibilities for progression and variation. Sufficiently advanced tech is indistinguishab

Make the character an inventor/engineer and suddenly you have endless possibilities for progression and variation. Sufficiently advanced tech is indistinguishable from magic. Equalization is not a very convincing argument. You can twist the rules in any way, this is fantasy. Make the firearms less advanced than a revolver, less available, less preferred, countered by magic, or simply make your work not revolving around combat.