Theres 2places where you might need to edit it..
1) You need to open up blog/code/BlogHolder.php and at about line 256 in that there is something like
RSSFeed::linkToFeed($this->Link() . "rss", _t('BlogHolder.RSSFEED',"RSS feed of this blog"));
You can set the text "RSS Feed for the blog" to whatever you want
2) In the rss() method in BlogHolder.php (same file as before) at about line 289 is this
$rss = new RSSFeed($children, $this->Link(), $project . " blog", "", "Title", "ParsedContent");
The bit in bold is the title you are talking about. You can just change that to whatever you want!