I think the best way to balance archers and reward skill is to make is so that:
- Archers can shoot relatively fast, rewarding quick aim and accurate flicks
- Archers have a high headshot multiplier, rewarding accurate aim and excellent prediction (at longer range)
- Archers do low damage on a body shot, due to how easy this is
- Infantry are stunned by headshots, but not by bodyshots (based on a threshold so point blank xbow shots would probably stun)
This means infantry can prioritize blocking headshots, giving them something more strategic and active to do while raising the skill ceiling for archers.
This might make archers too strong at close range (easier to headshot) but ideally a balance would be found.