The Nerf Nanofire Blaster, from Hasbro, comes with 3 darts and is recommended for ages 8+. You'll have trouble finding a blaster much smaller than the Nanofire. It's light and compact, and would sit nicely in a side or ankle holster, if I had one. The Nanofire is simple to use: load a dart, pull the plunger, and fire away! The additional darts store nicely on top. These darts do not fly as fast or accurate as many other blasters, but for its size and price, you can't beat the Nanofire. Although its small size may look like a "my first blaster," I recommend the Nanofire as an additional weapon while engaging in battles that include both far and close range fire.
Nerf Glowstrike Star Wars Qi'ra Blaster
Nerf N-Strike Modulus Mediator
Halo Blaze of Glory Blaster
Nerf Zombie Strike Wrathbolt