Few things: firing a musket from horseback while riding sounds like a nightmare, not to mention reloading it. Dragoons used hand blunderbusses, I say “pistol” because that is what it would be in the context of ToS. Said hand blunderbuss was actually called a dragon, which is where the term dragoon comes from. As cavalry units they were usually deployed with a lance, a dragon (hand blunderbuss/pistol), and a saber. Lances were ungodly efficient at mowing down enemies on foot while you ride them down, even if the foe in question was armored. The pistol would be held in the other hand to fire at someone on your other side while you lance his buddy and maybe trample someone inbetween, and then you would circle away from the melee to reload, maybe fetch another lance if you could because lances tended to break, and charge again. They were mounted skirmishers. The saber was a sidearm for when you were forced to dismount, your lance broke, or you had to fight another cavalry unit, because they could simply ride up next to you and render your lance useless. Dragoons were also specifically trained to fight on foot just as well as on horse, because as skirmishers it was inevitable that eventually they’d suffer a broken lance, drop their pistol, lose their horse, etc. and be stuck in a position where retreat was impossible.
But as to the lancer thing specifically, if they really did introduce a “lance” weapon that was wielded one-handed and had the power and reach of a two-handed spear while only being usable mounted, that would at least be an interesting differentiation from cataphracts.
@corsiritsmeurbrother
Where do you get the idea that lances weren’t a thing? Because they weren’t called lances? Swords weren’t called swords but they were still swords. A lance is just a spear designed for use from horseback. I’ve never heard of cataphracts being armed with swords (though certainly they’d have swords as a sidearm), as they were a heavy horse unit so that would make little sense. All of the marble and bronze depictions I’ve seen of cataphracts have them wielding what I’d be very comfortable calling a lance.
Also, cataphracts certainly predate the Sassanid empire, the Persians were employing heavy horse as far back as the Achaemenid, and the concept of the heavily armored cavalry charge using lances originated in Greece, most notably with Alexander’s companion cavalry - as well as the word cataphract itself. Granted, the Romans were as far as I know the first to deploy the heavily armored horsemen all decked out in scale coats, armored horses and all, so perhaps I should’ve said “Roman lancers” instead. Or “Byzantine lancers,” maybe that would be the most fitting if you really want to constrain your definition of what a lance is.
The Byzantines evolved the two-handed kontos the Persians and Romans used - which itself was a progression of the xyston, again a cavalry spear used by Greek companions - into the kontarion, which was designed to be held in the same way as the lance later European knights would use, in one hand and couched under the arm. So yes, cataphracts and their cavalry spears were the precursors to later heavily armored knights and lances, and effectively they were lancer units. Even the word lance is from the Roman lancea, albeit that was a much shorter spear designed to be thrown.
If you’ve ever seen a recreation of a kontarion, you’d know that thing can only be considered a lance. There’s no way to wield it in any manner other than pointing it at something and riding towards it. So we’ll go with “Cataphracts were just Byzantine lancers,” if you’d prefer.