There is a hacky solution if you want to secure the blog page but still use the feed in feed manager in the same site.
You can generate a random guid and add it to user.config like this:
<add key="InternalFeedSecurityBypassKey" value="3B05C70F-8399-421B-8FDE-CAABB7811779" />
ie in sql server you could generate a guid with SELECT newid()
if a guid is present in this setting then the feed manager will pass the guid in the request for the feed and the blog rss page will allow it to be served if it sees the correct guid.
However, it is a hack and NOT ENTIRELY SECURE, so use this hack at your own discretion. If someone can find out the guid then they can bypass the security also and get the feed data. It would not be easy to find out the guid but also not impossible.
If you use this solution you should use the blog feed as it is not use feedburner and it will not work with external feed readers like FeedBandit since they don't know the guid.
Hope it helps,