In current version the guard can use bow as a ranged weapon, and its functional with weaponry in Epic Knight mod by
magistu_ (https://legacy.curseforge.com/members/magistu_/projects)

However, it seems the guard only treat bow as ranged weapon in certain distance, and this distance is really restricted (and short). Whenever hostile mob is too close or too far away from the bow-using guard, the guard will treat bow as melee weapon and fist fight with the mob.

Current tested bow-as-ranged-weapon range is around 5.65 ~ 6.40 blocks. Guard will aim but not shoot the bow beyond this range and will start fist fight below this range if he is not stuck.