There are styles and weapons that are easy to learn and those that are not. I posted earlier about how to choose a MA that’s right for your character and, in a way, this is an extension of that.
What are some styles that can be learned easily? It might be hard to find them if we don’t know where to start looking. The answer is the kind that were developed for that express purpose. You want the martial styles that are still in use, the ones used (or were used) by military forces to train a large number of beginners for the battlefield. Alternately, take a look at basic self-defense training courses, these are techniques that are designed to be picked up quickly over the course of one or two sessions and without it being necessary for a master to look over your character’s shoulder.
Some occasionally overlooked weapons that are fairly easy to learn:
The Staff – ignoring the spinning, whirling beauty of the Wushu staff, the staff and the quarterstaff are very utilitarian, basic weapons. The strikes are basic and easy to pick up through rote practice, it’s a weapon that can be learned over the course of months instead of years and is fairly dangerous right out of the gate. Stick a metal tip on the end and you’ve got a spear, but that just makes it more deadly.
The Hatchet– The hand axe or the hatchet was one of the primary weapons of the Vikings, it’s more utilitarian and less romantic than a sword, but it’s another one of those weapons that doesn’t require much training to become proficient. It’s not that heavy and it is far easier to explain away to a city guard or a police officer than a sword or a firearm. Since the hatchet is essentially a bladed club, other club-like weapons also fall into this category: the crowbar, the wrench, and the heavy flashlight.
The Crossbow– Much like the Hatchet, the crossbow is less romantic than a longbow, but there’s a reason this weapon overtook it’s predecessor (and why firearms eventually overtook it). It’s a very easy weapon to train someone on, they will learn it quickly and with a surprising amount of accuracy. It and the bow have the distinction of true stealth, unlike the gun they can kill silently.
The Shotgun – this is a weapon that’s less romantic than the handgun or the rifle, but it’s much easier to learn. While most firearms are designed around ease of use, the shotgun’s scatterfire makes it easier operate in an actual situation. The downside, of course, is that you cannot hit a single target with absolute certainty, but buckshot will nail something. For a writer, the shotgun also provides a nice level of unpredictability, because even if the character is sure they’re going to hit what they’re aiming at, there’s a high likelihood of collateral damage in the process. For the audience, it’s a nail biting, desperate weapon and that’s a good thing.
The Slingshot – It’s easy to get a hold of, you can still buy them today, they sell them to children, and ammo for them can be picked right up off the ground. In some parts of America, the slingshot is still used for hunting small game. It’s also worth pointing out that in poor (and not so poor countries) the older version of the slingshot, the sling is still the weapon of choice for young children around the world. With practice, it’s level of accuracy is deadly. Use David and Goliath as a primer and you might come up with something interesting.