Do you know how it's possible to convert a layer symbology or an *.Lyr file to an *.style file?
You can export all the symbology used by your layers in a map document to a new .style file. Then all your symbol labels will become labels for symbols in the style which you can edit later on in Style Manager.
You have to add this tool by clicking Customize, then clicking Customize Mode. On the Commands tab, either type Export Map Styles into the “Show commands containing…” area or scroll down to the Tools commands to find the Export Map Styles tool. Click, hold and drag it to any toolbar in your interface.