My Video about Mastering Music in a DAW is well received, so let me amplify some of the most important messages from that video here.
It doesn’t really matter whether you load the Final Stereo Mix into a DAW or into a specific software (like Wavelab, to stay in the Steinberg/Cubase world) that was made for mastering. Of course, Wavelab features more specific tools that e.g. help with the track locators for CD/Vinyl and alike. But for Online Distribution this is pretty irrelevant.
And soundwise there’s no difference at all. You can totally master your music in a DAW. In case of Cubase and Wavelab they even share the same stock-plugins.