Reddit reviews The History and Art of Personal Combat (Dover Military History, Weapons, Armor)

There's a lot to unpack in this one. I like the ideas and prefer using things more akin to historical martial combat, but some of these are a bit adjacent to the usages. It is an excellent jumping-off point, so good work on that!

Blade and Dagger (Most commonly, Rapier and Dagger) would provide greater defense, yes, since you've got both hands involved and can easily catch a blade with either weapon. It also provided some distinct advantages with various guards or methodology. I would recommend looking into Joseph Swetnam's style, which originates from England, just to get a sense of how it could effectively spring-load the blade of the rapier for more vicious attacks. This could manifest in either greater damage, or "Reach." A Swetnam-sized Rapier and Dagger set would be 4 feet and 2 feet respectively, and I'd be willing to argue that - provided you have the correct footwork - you can easily attack someone within 10 feet and retreat before they can attack, though you can do this without the dagger. A major advantage of this weapon setup is that it gives you a "Cone" of defense, allowing you to guard two lines at once. This could be advantageous against multiple attackers, or provide an advantage on an opponent using a one-handed weapon.

Cloak and Blade (More commonly seen as Rapier and Cloak) would be used similarly to how you've mentioned, but was also used as a disabling and disarming technique. You could easily wrap the cloak around the arm of your attacker, or use the (often times, weighted in some way) edges of the cloak as another weapon entirely. You wouldn't be wearing the cloak while using it this way, it would be in your off-hand, moving in a circular pattern. Take a look at this video and others on youtube. In this particular one, they use their cloaks as offensive tools (throwing the cloak at the weapon, attacking the swords directly, tossing it at their faces) rather than just for parrying. The Martinez academy has a few up that are useful, but they focus on Spanish techniques, which have a very different intention of movement (More circular than Linear, focus on defense, lack of lunges, etc.) I would personally say that (for the sake of mechanics) allowing you a moderate/high DC disarm or grapple as a reaction when the opponent misses on an attack roll.

Gauntlet defense makes sense, but this would also fall in the vein of how most single-handed swordsmanship is applied. If you look at McBane, Talhoffer, or Giganti (among other 15th-18th century Swordmasters) they'll often employ the off-hand in these techniques. Now, wearing a leather gauntlet would often suffice for this, but it would come down to the specific instance. If someone is trying to perform - say - Zornhau, a slashing technique involving the whole of the body, I couldn't much use my Gauntlet to protect with that. I would, however, catch or beat a thrusting attack depending on the weapon, or attempt to grab my opponents weapon from a parry of my own. Or just punch them in the face. The big thing here is effectively "I would sacrifice my hand if it means I can kill you" - the way it reads now is "Damn, I'm glad I got my hand in the way of that!" There's a lot of versatility in this one, since you can use your off-hand for pretty much anything in a fight. The most common usage I see is using it as a parry/riposte - Someone thrusts at me, I beat with my hand, and immediately return a thrust as I parry with my hand. Maybe this can effect AC? I would argue it's certainly a Dexterity based skill.

There's a ton of books I would recommend, but this one is a good starting point. The History and Art of Personal Combat. The biggest issues with a lot of these manuals and treatises is that they're intentionally vague and obscure, oftentimes written in poetry that would require you to be well-learned, but also possess a prior understanding of the swordsmanship. This was done to protect trade secrets, so far as I know.

I like the direction and ideas you're heading in, I hope this helps! Keep it up! I look forward to seeing where this goes!