Technical skills basic outline:-

1. Remotely accessing and administering the server
2. Backend programming (PHP or .NET, SQL etc)
3. Understanding and implementing security systems
4. Understanding of HTML and CSS
5. Understanding of standards compliance and knowing how/where to check/validate
6. Understanding how to interpret/visualise/datamine logfiles
7. Understanding the HTTP networking spec (layer 5), headers and cookies etc

Additional requirements for high traffic/high value sites:-

8. Understanding and knowing how to implement load balancing/redundancy
8.1. Understanding clusters
8.2. Understanding Replication
9. Understanding DNS and how to configure (this one is a much misunderstood area)
10. Optimising databases, stored procedures etc.
11. Optimising webservers, understanding performance metrics

I'm sure there's some categories I've missed. If you're in a position where you need to hire, do not rely on the above list as exhaustive.

Level of expertise required will really depend on the importance of the website. Ideally you need a complete expert on all of the above. That may not be possible of course within the employment budget though.

So how important is the site to you, how large is it (traffic) and how much money does it generate? Work backwards from there.

You specifically mentioned "technical" so I've stuck to that, but of course in the real-world there are overlaps between design, marketing and technical configuration.

Thx for your info and i admire this site very much (except for the interface).

shd i prior experience as a web developer before being designated as webmaster

That really depends more on the job description than the job title.

How would you define "webmaster"?