Police called to a rumpus outside a shop found a drunken man who kicked one of them in the shin.
They then investigated further and discovered he had previously brandished two knives.
James McMullen, 55, of Locking Road in Weston-super-Mare, pleaded guilty to assaulting an emergency worker and threatening with a blade on March 31.
Judge Martin Picton jailed him for 24 months.
He told McMullen: "You have a serious problem with alcohol now and drugs in the past.
"I just don't see you surviving in the community at the moment."
Edward Hetherington, prosecuting via video link due to coronavirus lockdown, told Bristol Crown Court police received several calls to an incident outside the One Stop Shop in Locking Road, Weston-super-Mare.
They found McMullen in a nearby doorway drinking from a bottle of methadone (morphine substitute).
When he was approached he kicked an officer in the shin and police deployed a spit hood and PAVA spray in the course of arresting him.
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Scrutiny of the shop's CCTV showed McMullen outside, armed with a knife in each hand, swinging the blades at a man as they argued.
McMullen was interviewed and told police he was ill with coronavirus symptoms.
The court was told he had previous convictions for possessing knives and received a 12-year prison sentence in 1996 for slashing someone's throat.
James Tucker, defending via video link, said his remorseful client had been homeless at the time and battling heroin addiction but had relapsed into daily alcohol use.
