The most similar thing I'm familiar with as an affixing method is more usually done with aluminum (modern, of course) or lead/lead alloys. With poured brass into a hollow handle rather than into a mold forming a solid one-piece cast brass handle, it seems unusual. Don't get me wrong; neither do I know everything nor are unusual things unusual
see if you follow that one
The general type of the handle, hollow metal, ribbed, etc. is certainly a thing I'd seen, fairly often and in many verieties, but usually with the tang just passed thru and piened. This attachment method should be stronger, and as noted, should help keep the tang from rusting. I'd think the sword is fairly handle-heavy? But the narrow grip and fairly thin bowl may keep things within reason, and even the cut-out may have to do with a balancing concern (pure speculation; such holes are fairly usual, except that this one goes all the way to the tang, and so seems added on or otherwise nonprofessional/unusual in some way)? I'm unclear as to what metal the hilt is made of; is it brass, or iron? I'm right with you on the private issue cutlasses/hangers, the maritime ones often having variously ship-board made hilts, many sharing features in common with Oceaninc East Asian swords (thin sheet metal knuckle guards ala Visayan swords, occasional habiki-like bolsters......), and often partaking of traditional sailors' crafts such as scrimshaw, engraving, knotwork. I often enjoy the quality on Western military/overculture swords, but I really find the folk level plastic art more interesting in general. It is often spoken of as if this did not exist in Europe, as if the overculture/industrial culture WERE European culture; I do not believe this is accurate; there seems to be (to this day, even) a strong strain of peasant/rural/underclass/lowtech culture that is often ignored or looked down upon, but which I find quite interesting and interestingly comparable to other traditional/preindustrial cultures; this is certainly notable of its material culture, including blades, which are more often with a soft body and harder edge (often welded/inlaid), and as I've metioned about hangers, more often of wedge cross section, than military/government/etc. swords. And it's also interesting how it interfaces with foreign material culture through international sailor subculture on the empire of the waves. I find user made/field made dress particularly interesting; sometimes it is of good or even particular quality, and other times I feel compelled to remove it from a good blade and replace it for nonfunctionality.....This one looks perhaps professionally made, but user-affixed? Just a guess. Sounds like it's pretty dang solid, anyway, which is a big good in a sword handle