Sorry to answer so late but I was away on deployment, the first style of coa are taken from the Royal Navy, it was not before 1949 that the Belgian Navy was transferred from the ministry of transport to the ministry of defence, since that year we had the new coa, hope that it answered your question
small update for the crest of the BNS Stern, she was decomissioned and sold off to an civilian buyer early this year, the BNS Aster, is also decomissioned,stripped of all usable part and is awaiting decision to be sold off or broken up, will keep you updated on new developments