The textures on weapons and shields could do with becoming less bright. This would fix a major flaw in the graphical representation of arms in AoE 4. At the moment, most weapons in the game are not affected by other light sources, this causes them to have a flat appearance. On certain weapons, this also causes metal on weapons to have no difference in sheen from their wood pieces, giving the two materials a similar appearance.
Some units have weapons where this isn’t the case, such as the Handcannoneer, Musofadi warrior, and the Ghazi raider. If all of the other units in the game had their weapons altered to not be emissive then I think that this issue would be resolved. The weapons are still plainly visible without having emissive behavior, so gameplay would not be negatively impacted.
Overall, it seems like the change would be very easy to implement if the texturing was done correctly on the items in question. They just need to lose the emissive behavior that they currently have.