Rather than have to type in three different fields, it would be easier to simply copy/paste the URL from WP. This includes the first three fields.
Also, if the %?? hex encodings were accepted as user input for URLs, that would be better yet. (For example, the %C3%A3 in http://en.wikipedia.org/wiki/Pirah%C3%A3_people )
Maybe I will do a redesign of the whole UI some day, where I could include it. As a temporary solution, I could offer you a parameter in the url of WikiBlame, where you could add the article from wikipedia. Would that be ok for you?
I will also do something to support articles containing % - soon.
Will be continued on https://github.com/FlominatorTM/wikiblame/issues/19