This is the most elegant ball pein hammer I have ever seen. But it is simply a ball pein hammer, used for all the usual ball pein hammer jobs.
About the thin handle. A lot of hammers were given slender handles like this. This one is no more slender than the handle on my 2 pound straight pein blacksmith's hammer. The slendered handles give more whip in use, and make work easier.
I don't have to imagine hitting things all day with hammers. With a good hickory handle, I haven't found any great effect on my hand. A few years back, I spent 12 hours at the anvil one day, and 8 hours the next making some fairly heavy wagon parts. No problem.
But the whippier handles turn a mere club into a fine tuned tool.