Archer guards keep their bow drawn without holding the animation. They keep the bow drawn for excessive long times, possibly indefinitely, which results in the next player getting close to multiple guards to be "shotgunned" by all guards at the same time, which can result in instant death.
Archers guards also do not keep their current target and randomly switch between targets in range, making it hard to impossible for shield tanks to draw archer fire first to allow other classes to get close without being threatened.
Archer guards also have bugged models when facing players, sometimes allowing positional styles to hit when the model is showing their backs to the player, and also not having ANY side for side positionals in some cases.
For completion sake, they also do not hit back when engaged in melee. (This was previously reported)
The LOS issues of guards shooting through towers/keeps are not guard related, they are keep models LOS related.