Paul Howells made the discovery at a field in Coity, Bridgend, on 8 May 2015.
The hoard included a large bronze flat axe with a wide-blade edge and a small bronze axe chisel dating back to 2200-2050 BC.
Late Bronze Age tools and weapons were also found two sites in Llanharan, Rhondda Cynon Taff.
A dig at the Coity site found the two axe heads had been placed underneath a large limestone capping stone.
Archaeologists suggest hoards of this kind were buried during religious ceremonies, possibly as gifts to the gods and goddesses.
The two Late Bronze Age hoards found at Llanharan were discovered in March 2015 during a metal-detecting rally on farmland.
They included bronze socketed axes and two bronze socketed spearheads, dating back to 1000-800 BC, found at two sites half a kilometre apart.
National Museum Wales hopes to buy the items with funding from the Heritage Lottery-funded Saving Treasures: Telling Stories project, to put them on display.
Early Bronze Age axe heads found by a metal detectorist in south Wales have been declared treasure by a coroner.