Honestly I wouldn't be that interested in melee weapons, if they were going to be added I hope they would use a system like Mount and Blade attacks and blocks.
Bow seems like it would be fun, but unreasonable and unrealistic in ARMA 3. Crossbow is a effective weapon that many people use for hunting, and can easily be just as effective in killing. The Crossbow may only be a fun feature in the game, but it wouldn't exactly be "unrealistic".