Thomas Detry (69), Edoardo Molinari (70) and Darius Van Driel (70) also finished in a tie for second.
Previous champion Paul Casey, who won in 2019, shot 68 and finished sixth at 4-under.
The tournament at Green Eagle Golf Courses was shortened to 54 holes — and its start postponed by two days to Saturday — to allow players and tour staff from Britain extra time to deal with Germany’s travel restrictions.
Armitage’s win is the fourth consecutive victory by an English player at the event after Casey, Richard McEvoy and Jordan Smith.
Declining coronavirus infections allowed fans to attend a European Tour event for the first time since 2019.
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