Based on my understanding of the particle が, the title of the manga アカメが斬る should be translated in English to "Akame kills" or "Akame will kill (someone)". There was never any question in my mind since it seemed so obvious that が is marking the subject and indicating that アカメ (as opposed to someone else) is in fact the one executing the verb 斬る.
However, I was reading through a fan translation and the following explanation was included in the margin of the page when a character states アカメが斬るんだ in context:
This line is so poignant that I can't do it justice in the translation. the line in Japanese is "Akame ga kirunda" or "Akame ga kiru", the title of the manga. The title, which is normally interpreted to mean "Kill Akame" is said exactly the same way here and means, "I want you, Akame, the be the one to kill me." In essence, it kind of makes you look at the title as "Akame is the killer" or "Akame kills".
I would never have assumed that アカメが斬る meant (or even could mean) "Kill Akame". However, this translator, who presumably knows Japanese pretty well, goes so far as to say it is the usual understanding. Could someone please explain this use of が (if in fact the translator is correct).