Matthew Glynn admitted to police that he had held right-wing views but now found them “wrong and disgusting”.
Officers found right-wing material – including posts by Britain First – on the former carpenter’s Facebook profile.
They discovered a cache of more than 200 knives, swords, axes and blades at his home in Bristol, as well as an IED under his bed.
He possessed a tennis ball grenade, which was designed to be filled with explosives, lit and then thrown.
Glynn also had a Wolverine-style knife with four sharp blades, believed to have been ordered online.
Detective Inspector Dave Lewis, of Avon and Somerset Police, said he had never seen such a weapon in his career.
“Matthew had an extensive collection of knives, axes and swords, blades,” said Mr Lewis.
“Probably the most horrific of these is something that has been described as a wrist knife.
“It is like a gauntlet with four very sharp blades coming off that you would hold with a fist and have four knives coming off the top of your hand.
“I’ve never seen one of those before. I understand it was purchased on the internet. It is a horrific piece of equipment.”
He described the bomb-making equipment and crude devices as “potentially fatal” and “effective”.
“In this case, Matthew Glynn, we looked at what potentially were his motivating factors,” Mr Lewis said.
“We did find some right-wing material on his social media. We asked him questions about that.
“He stated that he did hold these views up until approximately two years earlier and no longer held these views.
“We could find nothing else in his social media that suggested he’d carried on expressing right-wing views.”
Mr Lewis said items relating to bomb-making, such as handbooks, were found at Glynn’s home.
“There was nothing that you would say was right-wing and led him down a path,” he added.
Police said the Crown Prosecution Service was involved with the case at an early stage.
“Their decision was this didn’t meet the threshold for terrorism offences,” the detective added.
“I don’t know how long before two-and-a-half years ago now he would have held these views; however, in interview he was asked about the age of the social media posts and he told us that he held these views up until about two years ago but now felt these views were wrong and disgusting.
“When questioned about that, he said that a woman had corrected his thinking. We’ve never identified that woman, we’ve never spoken to her.”
Bristol Crown Court heard that the Attorney General authorised charges against Glynn under the Explosive Substances Act 1883.