I have a ring bearing the Hohenzollern cross which was given to me by my wifes great grandfather, a WW1 veteran. He took it from a German soldier he killed with a bayonet sometime in 1915. 'Dada' was a tall man but he said the German he fought towered over him, I can believe that because the ring is too large to fit even on my thumb.
After the war 'Dada' came home, overcame his wounds and raised a wonderful family. A modest and gentle man who everyone liked and respected, with not a shred of hatred in his heart.
How you can switch on and then switch off that warrior instinct amazes me. My dad was the same.