I would like to arm fruit bats with weapons in this modern age (2017), but I don't know what to arm them with. A couple of bits of info:
- They are as intelligent as humans, so that is not a barrier.
- Their feet are prehensile and able to grab and use weapons.
- They need to stay in flight at all times when using the weapon.
- The weapon needs to be quiet, and when used, not give away the presence of the bat. (Such as a loud gunshot, explosion, or plume of fire)
- The weapons could be used for personal protection and/or military use.
We are talking about flying foxes, as they are sometimes called, with a general wingspan of 1.5 meters (4 ft 11 in) and weigh about 0.65 - 1.1 kg (1.4 - 2.4 lbs). Information pulled from Wikipedia.
They can lift up to 40 grams (~1.4 ounces), as they can lift 6 week old infants, and the weight is provided at zooborns.com, although there is a good chance they can lift more, but information of this kind is really hard to find. If an answer requires the bat to lift up to 250 grams (~8.8 ounces), it will work.
They are fighting primarily human targets and each other, and their primary roles would involve reconnaissance and scouting out enemy positions, as well as taking out priority human targets (commanders, enemy snipers, or other bats). Due to this goal, they will mostly travel alone.
Because they are so small and fragile, weapons which do not give away the position of the bat would be best, with "louder" weapons (such as grenades, any incendiary weapon, most guns) only being used in emergencies.
In any case, most weapons could not be used, as bats are small and are not very strong, so guns would be mostly ruled out. Tiny guns would work for anti-bat measures, because bats are small and do not take a lot of effort to kill, but the larger guns to kill humans are heavier, and would probably not be able to be used.
Unmodified grenades would not work, as they are almost too bulky for the bat to handle and maneuver effectively, and are too loud. Smaller grenades have a chance of working, if you also made them quieter, somehow.
Sprays might work, but they require you to get very close to the target to be effective, within 10 feet, according to modelmugging.org.