Hi everyone, I'm one of the "forum participants who specialize in Indian arms and armors" here to give my 2 cents
. Though I do agree with the dates speculated by Turkoman, I must express my doubts about the hilt being from Thanjavur (tanjore) and the blade being more northern. Instead, I would offer the attribution of the whole piece coming from the southern deccan, based on its form and manner of decoration.
Firstly, for the blade, while it is of a more simplistic northern form, "the north", generally speaking, did not make katar blades individually to be later mounted in different hilts. Indeed, while most northern katar blades are forge-welded, brazed, or peened onto their hilts, the blades are not typically produced from very far away, and instead the blade, hilt, and assembly centers are all close enough that most regions in northern india developed their own distinct katar styles, with different styles of blades and hilts from one another. Additionally, northern katars invariably have "shoulders" extending from the sides of the blade that fit with cutouts in the sidebars to facilitate being brazed/welded/peened together. These shoulders would have to be removed to allow the blade to fit in a more southern style of hilt, so I think it is unlikely the blade on the katar here is from the north.
In regards to the hilt, my attribution here is primarily due to the style of decoration. Thanjavur schools, simply speaking, produced items that were way more ornate than this, and, due to the region being overwhelmingly Hindu, Thanjavur products almost always feature explicit Hindu iconography in the form of animals and mythical beasts, and other beings that can be related to hindu deities explicitly. The fact that the decoration here is so relatively abstract and can be best described as "floral" means a more northern, islamic school is a more reasonable attribution for this hilt. Of course, too far into the north and this style of katar hilt is completely dropped, so that's why I give "southern deccan" as a compromise for my attribution.
Finally, I must give a "grain of salt" style of disclaimer here as most of this information comes from my own private research, none of which has been published or peer-reviewed or anything of that sort, so I cannot provide any official sources to back up my attribution.