I have restored a few antiques over the years, some for myself and some for other people. I do frown upon melting antiques down like some YouTubers do, and destroying old blades and forging them into new modern knives. I don't consider handle replacement of a broken or decayed handle destructive, in my opinion (Some people disagree) it would be a type of preservation and restoration. The same way removing active rust is helping the blade and not harming it.
I would also replace the handle, especially if water can get inside it because of the damage, you don't want wet rotting material touching the blade tang and eating away at it, that might lead to it completely breaking and pitting to the point of no return.
I also believe that it's okay to responsibly use antiques, I have restored and cut with antique swords that are hundreds of years old. I have a British 1845 officers military sabre that I restored and still use to test cut with.
I also have a collection of antique hammers that an old blacksmith sold me when he retired, they were older than him, and I use them to this day, especially the small ball peen hammer I use that to set rivets all the time.
I think you might need to replace the handle pins, it's possible you could hammer them out and try and salvage them, but I think you will most likely need to put new pins in. You can buy brass rod on ebay at any thickness and length. I buy all of my brass rod on ebay for handle pins and rivets. Just measure the tang holes and buy some brass rod. You can grab some Micarta and wood scales from ebay as well for a good price and restore it for a low price. Making handles is actually pretty easy, you can do the whole thing with just an angle grinder flap disc, or set of hand files, expensive equipment not needed.
