Dniro Barrett and George Simpson were caught on CCTV dragging the two victims across a car park before beating them up and demanding their money and phones.
One of the victims was slashed with a knife, but the blade only went through his trousers and narrowly missed his groin. Both attackers' faces were concealed by hoodies, scarves or face masks.
They were caught because shocked Christmas shoppers noted the number of their getaway car and police intercepted them as they headed home to the West Midlands.
The knife and a wallet which was stolen during the robbery in Exeter were found when the car was stopped on the M5 near Weston-super-Mare.
One victim suffered a fractured cheek bone and eye socket in the attack, which started in Fore Street before the victims were dragged through the car park of the Mint Methodist church.
Miss Bathsheba Cassel, prosecuting, said the two victims were in Exeter on the night of December 20 last year when they were waylaid by three men, two of whom were Barrett and Simpson.
They were dragged into the church car park where Barrett lunged at one of them with a large knife, narrowly missing his groin and cutting open his trousers.
The same victim was hit in the face with such force that he suffered two broken bones. His wallet containing £30 was found in the VW Polo getaway car when it was stopped. He told police he was scared for his life during the robbery.
Mr Andrew Kerr, for Barrett, said he has mental health issues arising from a troubled childhood but is still young and determined to make a new start on his release.
Mr Lee Egan, for Simpson, said he was not involved in the more serious violence and had not played the leading part in the robbery. He had been a talented rugby player in his teens and had trials with the Worcester Warriors. He is young and not heavily convicted.
Barrett, 21, of Chestnut Grove, Kidderminster, and Simpson, 20, of no fixed address in Worcester, admitted robbery. Barrett was jailed for five years and six months with a one-year extended licence and Simpson for three years and nine months by Recorder Mr Leslie Blohm, QC, at Exeter Crown Court.
He told them: “This was potentially a very dangerous attack. This was an appalling crime which could have had far more serious consequences.”
The judge said Barrett was a dangerous offender because he has previous convictions for robbery.