Webmaster is a catch-all term that covers many different sets of skills. A lot of us can do all of it, but very few people are actually good at everything.
- Designer: HTML and/or graphic design skills. I would argue on site SEO is part of this
- Back end developer: this one can be split further into coding, database design, etc.
- SEO: off-site link building.
- Content creation: most commonly a writer, but you might be an editor, artist, photographer, video director....
- Community manager: the reason a forum or similar works
- Entrepreneur: organising other people to do all of the above, finding funding, etc.
Have I missed anything out?
MY strong point is writing, I am a competent (not great) back end developer, but struggle a bit with getting front ends done. I can cope with the rest. What about you?