Most European chivalric orders, both historic and otherwise, as well as many other awards issued were cruciform (for different examples of styles, see the Pour le Mérite, the Iron Cross, and the Victoria Cross). All of the orders listed above, as well as many others, were open to Jews and many of them required display of the insignia by recipients.
Would wearing the cruciform insignia of orders be allowed for the recipients, from a halachic perspective?*§
*The issue that I could see would be the wearing of something shaped like a cross, as it is associated specifically with Christianity.
§I have heard that even the WWII issue of the Iron Cross may have been issued to individuals who were openly Jewish. This would introduce an additional problem, as the hakenkreuz (swastika) is associated with pagan and Hindu religious symbology.