If you believe that the bow is too easy then take a look at Admin Weapons Mod for Minecraft. You’ll get not just a gun and assault rifles, you get a unreal powerful weapon. 12 different weapons available to you, and each of them has completely different properties. For example, a poisonous TNT will destroy everything in a radius of 10 blocks. Or admin gun that destroyed everything including the players, mobs and blocks. Each weapon has a crafting recipe that will not cause difficulties.
Be careful, some types of weapons can destroy a huge area so we advise you to save your map. Also, there may be lags.