Martin Luther took this as his "coat of arms," though he was not nobility nor did he fight in a war. This has sometimes been adopted as the standard of Lutherans, and you can see it in some Lutheran places.
Underneath many Luther-Roses is the phrase: "Des Christen Herz auf Rosen geht/Wenn’s mitten unterm Kreuze steht." (The Christian’s heart stands on Roses/When he stands under the cross."). Luther describes his rose in a letter to Lazarus Spengler (8 July 1530) "… the cross is black, mortified and full of sorrow, and the heart is in its color … Such a rose stands in the middle of white roses, pointing out that faith sits in joy, trust, and peace … And around such a field there is a golden ring that such holiness exists eternally in heaven ..."
I guess that's it by way of explanation.
