When you're in block editor, you can save block to an external file. Much like the old WBLOCK command. To do this, when you're in the block editor run the command BSAVEAS, or in the ribbon click on the Open/Save flyout and select "Save block as" option. Here you're prompted to save the block with a new name. Here, instead of saving as a new block, you tick the option down the bottom "Save block definition as drawing file" and press OK. You will be prompted to save the file externally. This will export the block into it's own dwg file. If you open the file itself, you will be prompted to go straight into the block editor. Most of my block library has been sorted this way, as I use tons of dynamic blocks that I create almost on a daily basis.
