>>713410814 (OP)
1. Make enemies stronger.
Archers get better the stronger enemies are. 3 Houses is a great example of this, where you put an Iron Bow + in the hands of literally every one of your units.
2. Remove the growth unit mindset from archers. Part of the problem with archers is they inherently get fewer kills than other, similar units. Good archers are thus biased towards bases even harder than other units. Look at FE9 Shinon, where he's a sturdy body, who fucks in combat, even if he only gets 1 per turn. Units like Rebecca are dogshit because she will never actually get the kills she needs to grow. Early archers should be powerhouse units that don't actually need to be protected, they can bodyblock for others, and are doing good fuckin damage, not "chipping".
Situational 3 range. Somewhere between literally everyone using it in 3 houses, and it being tied to one shitty bow. Longbows should be more accessible, and presented as complete equals to the Steel Bow. You choose might or range, for the accuracy and weight penalty over iron. Maybe remove doubling for them or something. Point is, there should be more than the one longbow that drops off some chucklefuck in a castle box halfway through the game.
What does NOT help
More enemy fliers: Fliers actually beat archers 9/10 times. They have better move, can go over obstacles, and usually are actually among the best counters to archers.
1 range counters: This DOES technically help, but it just turns archers into shitty handaxes, and is the most cowardly way to do it. Maybe tie it to a particular bow, and it's better.
Nerfing javelins and handaxes. Doesn't help because bad 1-2 range is better than 2 range, and the most common 2 range javelins and handaxes are actually being used against, are javelins and handaxes. Nerfing javelins and handaxes MOSTLY solves itself, and if anything buffs magic, because now magic is 1-2 range, still fucks bows, and now is the only real 2 range game in town.