Are folding Xiphoi practical?

Question

I have a character that fights with a pair of xiphoi (double-edged, one-handed shortswords used by the ancient Greeks). These swords are stored in thick nylon sheaths around the character's forearms, which have Velcro straps to help secure them in place when not used. These xiphoi have 50 centimetre-long stainless steel blades that fold down into the handle, keeping all blade parts unexposed in a manner similar to the Belgian Folding Cutlass and when a steel thumb release is pressed, the blades swings out for use and lock into place.

How practical would such a weapon be?

Answer 1

You're basically talking about extra-large switchblades (of the folding, rather than spring-out, variety), which is both good and bad. These weapons are practical at the smaller scale, but I see three potential problems with scaling them up.

One is that it will wreak havoc with your internal balance. The weight of the spring mechanisms on the blade, combined with hollowing out the hilt to make room for the folded blade, will move the center of balance forward. Slashing swords tend to have their point of balance way back in the hilt, for greater control; moving it forward makes it more of a chopping weapon like an axe, which requires a different fighting style. A stabbing sword might actually be more practical here, since it doesn't care as much about balance.

The second issue is that the hinges themselves are weak points, in that they can both be broken relatively easily and have the potential to fold up in combat. This is especially bad since your balance problem, as mentioned above, is biasing your weapon towards big power strokes. The best way to solve this is to minimize the number of hinges, but that makes your whole package longer. Having a 50cm "hilt" on a sword isn't inherently bad, but it will mean extra practice to get used to it.

The third issue is the raw force of the spring(s). Switchblades are small, but the mainspring can still put out a surprising amount of force when triggered. You're talking about a blade 10x as long, probably several times thicker in cross-section, with a proportionate increase in the amount of force it takes to swing it out. You'd have to be careful not to drop them just from the sudden torque.

Answer 2

If you want to know how practical the hidden blades from the Assassin's Creed videogame series are, you can experiment with them yourself. You'll get better results than asking online.

I like people who get around to building things, like Colin Furze. He as built a functional hidden blade, but his is quite awkward IMO. The folks from Man at Arms have built what I think to be a better one, and tried it on a water melon. Seems to be good for stabbing.

If you have not the skills nor the resources to repeat the experiment... Get a dagger or a similar weapon and tape it to your forearm - pad it with cloth or leather. Then try it on something (something that is not alive, please). You will notice that this weapon is terrible for slashing, compared to being used as it was intended to be used. It hurts the forearm if you hit something with it in a slashing motion. I tried this with a makeshift wooden dagger lookalike that had no edge, so as to avoid risk of personal injury. If you do it with an actual blade, you are a candidate for a Darwin Awards honorable mention, or even the award itself.

So all in all... If you are going into a sword fight, you should bring a sword. If you want to assassinate someone, a small switchblade will be smaller, far easier to conceal, and less likely to break due to having less moving parts. It will also be less conspicous. Ditch the hidden blade.