There are a couple of reasons I changed the fiberglass handle out for a wooden one. This was a stubby handle and you will get more force with a longer handle. Fiberglass handles are held in by epoxy and will come loose faster than a wooden handle. I have 20+ year old hammers with wooden handles that are still fine, but not a single fiberglass one that lasted more then a year or two without its head coming loose. The "grip" they put on most fiberglass handles will pinch your hand.
Fiberglass handles are usually fairly chunky in section and will cause tendonitis very quickly. The best handle shape for forging all day with is a simple rectangle with the corners well rounded off.
So why go to the trouble of swapping handles there’s no reason to do that
There are a couple of reasons I changed the fiberglass handle out for a wooden one. This was a stubby handle and you will get more force with a longer handle. Fiberglass handles are held in by epoxy and will come loose faster than a wooden handle. I have 20+ year old hammers with wooden handles that are still fine, but not a single fiberglass one that lasted more then a year or two without its head coming loose. The "grip" they put on most fiberglass handles will pinch your hand.
Fiberglass handles are usually fairly chunky in section and will cause tendonitis very quickly. The best handle shape for forging all day with is a simple rectangle with the corners well rounded off.