Quick question- was the Rakuyo from Bloodborne modeled after a real life weapon? I’ve seen similar designs in other things. If you don’t know what I’m talking about, it’s pretty much a sword, with a partially hollow hilt that you can attach/detach another knife in.
The blade itself is based off of a Japanese military sabre. To be clear, I’m talking about the primary blade, not the detachable dagger. The second detachable blade is something of From’s own creation (or it’s a Berserk reference.) The second blade may be based off a 19th century Japanese bayonet, but that’s mostly an educated guess.
Spiked pommels are quite real. When fighting in quarters too close to strike with a sword, bringing your pommel down on your foe’s face is a valid tactic, and spiked pommels build off this idea. I can’t remember seeing a full dagger attached to a pommel before, but the idea isn’t particularly strange.
As a detachable weapon? Not that I’ve ever seen. In general, Bloodborne‘s weapons are implausibly complex, to the point that most simply wouldn’t function in the real world. There are a few exceptions: While real Pallasches didn’t incorporate firearms, combining a single shot firearm onto a sword wasn’t, completely, unheard of in the 17th and 18th centuries (which is when the Pallasch dates to.)
The “least” realistic trick weapons in Bloodborne tend to be the ones that are articulated or include detachable components. Things like the Threaded Cane, the Kirkhammer, Ludwig’s Holy Blade, or the Blade of Mercy, would all be grossly impractical or impossible to produce. The guys at Baltimore Knife and Sword made a replica of the Saw Cleaver, which illustrates a lot of the engineering challenges inherent in trying to replicate Bloodborne‘s weapons. You can find the youtube video here.
The game is a, literally, a nightmare, as the various characters attempt to deal with elder cosmic gods, of the Lovecraft variety, so the fantastical elements blended into the gothic art style do serve a legitimate purpose. The melee weapons are, without exception, an extension of this concept. They’re twisted, vicious, creations, designed to tear people (and monsters) apart in singularly unpleasant ways. That many of these same weapons are wielded against you by bosses and other hunters just cements the horror.
That said, the idea that someone would have taken a Japanese Guntō and attached a bayonet in a reverse grip isn’t completely insane, while the bayonet’s locking lugs could still allow a quick release option, converting the weapon back into two distinct pieces. I mean, it’s possible, and in comparison to some of the other weapons in Bloodborne, it’s almost plausible. Would it work? Probably not. I doubt it would hold up in combat. But, this would be relatively easy to rig up as a display piece.
So, the short version is, you could make one you’d use for cosplay, but making one that would actually work as a combat weapon is a lot more questionable.