The discovery includes 268 complete axe-heads, one of the biggest hoards ever found in Britain. The find, as it constitutes a "prehistoric" metallic object qualifies as "Treasure" and is the property of the Crown.
Archaeologists believe the hoard was buried in the field as some form of ritual offering to the gods.
Grandfather Mr Peirce, from Ringwood, Hants, said: "When we took them out of the ground, some of them were so pristine you would think you had just bought them at B&Q yet they were 3,000 years old."
There were so many of the artefacts that the pair couldn't collect them all so returned the following day with fellow detectorist Brian Thomas,75, to gather the rest.
Mr Peirce, who has been a metal detectorist for five years, added: "We went back and dug in another hotspot and found a load more.
"We were very lucky because there was not much else in the field.
"If we had tried another place or walked in a different direction, we'd never have found them."
Mr O'Connell, 62, who has owned the farm for four years, said: "Within about half an hour of Tom searching, he came rushing over to me looking shocked.
"During the war, a plane had crashed in the same field and for a minute I thought he had found a bomb.
"We went back up there on my tractor and saw the axe heads. I didn't have a clue what they were - I thought it was scrap metal at first.
"I have owned the farm for four years and had no idea they were up there. It is very exciting."
The find will now be valued, and the finder and the landowner will split the market value, which is estimated to be £80,000.
It's this reward scheme under the Treasure Act which encourages the reporting of these finds. The difference between this policy and the typical approach in source nations is it encourages finders to come forward with finds; however it also encourages more metal detecting, which can be seen as a trade-off. The compensation scheme is a pragmatic balancing of interests, which places a higher value on the acquisition of the find, and bringing discoveries to light, rather than leaving objects in the ground. I think it's an excellent policy for the UK, but it may be questioned whether such an approach would work as well in other nations without the economic resources to fund the scheme.
Those objects which don't qualify as treasure are subject to the voluntary Portable Antiquities Scheme. Treasure basically includes precious metals (i.e. gold and silver), prehistoric base-metal like these bronze objects, and objects found with them. Since 1997, objects which don't qualify as treasure can be recorded by the Finds Liaison Officers which have forged connections with local metal detectorists, and have compiled information which has led to a more complete understanding of important sites.
I should note, that it's my understanding that Greece and Italy both have similar rewards schemes, but not a lot has been written about them to my knowledge. My initial conclusion is these schemes are not funded as well, and have not produced the kind of results the PAS has. I believe both nations reward finders at something like 25% of an object's value if it is discovered by chance. If any readers have knowledge of these kinds of rewards schemes I'd appreciate a post in the comments.