A flurry of late goals - including a header from Miroslav Klose that saw the striker surpass Gerd Muller as Germany's all-time record scorer - enabled Joachim Low's men to record a comfortable victory in their final warm-up game before heading to Brazil.
However, it is the injury to Reus that will dominate the headlines after the Borussia Dortmund forward was carried from the pitch late in the first half in visible distress after appearing to twist his left ankle.
Armenia's equaliser came with 21 minutes remaining, yet the hosts subsequently pulled clear with further goals from Lukas Podolski, Benedikt Howedes and Klose before Mario Gotze rounded off the scoring with a late brace.
Germany can expect stiffer opposition in their World Cup opener against Portugal on June 16, but will surely take heart from the way they finished Friday's match at the Coface Arena in Mainz.
The first ended then on a sour note for Low's men, as Reus was helped from the field in some pain following a tackle from Artur Yedigaryan.
Reus' replacement Podolski had a hand in Germany's opener as Schurrle found the net seven minutes into the second half.
Podolski rifled a fine finish into the bottom corner from Ozil's neat pass, and Howedes swiftly made it 3-1 by converting a rebound after Berezovsky's brilliant inital save from his header.
