Claiming archery needs to be nerfed because you got 1 shot once is like if I claimed melee needs to get nerfed because I got 1 shot a few times.
Again, archery is a completely different thing from melee, and different from crossbows and throwing too. I can live with getting one-shot by cav, in melee, by a throwing lance or by an arbalest, but not by an archer. An archer has too many pros to be able to one-shot medium infantry. Crossbows has high reloading time, throwing has low ammo, melee must be in the danger zone to even have a slight chance of making a one-hit. The archer can run and gun, have good kiting abilities, can easily dodge cav with their movement while still being able to shoot.
You need to take a bunch of other stuff into account (who shot you/what was his build/what arrows did he use/were his items masterworked/how close were you to the archer/did speed bonus apply to him/ did you take the maximum amount of damage from the randomness of archery damage).
Low to medium range, not running towards him. He was not at an elevated position. I don't know his build though. However with mail hauberk, mail mittens , 18 strength and full health you should be able to survive one arrow.
But happening once and happening consistently are two separate issues.
Yes, it is, but archers should in no circumstances one-shot medium infantry except for headshots of course.