I would definitely agree with
Excalibur (1981), my favorite retelling of the Arthurian legends.
There's also
Lancelot du Lac (1974), which is a much more intellectual, minimalist film. I personally loved it for its strikingly original take on Camelot (comparing Camelot to a Versailles-like existence while people suffer all around them). I would guess that it's a movie mainly for film buffs, but I could be wrong. It is available on Netflix.
Of course you can't go wrong with
Monty Python and the Holy Grail or
Jabberwocky.
Jabberwocky was very different from
The Holy Grail, but I did enjoy it, and it's worth it for the opening scene alone.
I'm not sure why
Rob Roy qualifies as a medieval film, and it's comparisons to
Braveheart stem from the fact they came out in the same year and both deal with Scotland. It is actually much more accurate, but that's because
Braveheart is pure fantasy (on par with
Excalibur in terms of accuracy), and
Rob Roy takes place roughly 415 years after
Braveheart. Definitely recommended though; better written, better acted, and yes, more accurate than
Braveheart.
With Joan d'Arc, are you referring to
The Messenger: The Story of Joan of Arc (1999) or the tv movie
Joan of Arc (1999)? If you haven't seen the
The Messenger, I would recommend it. It's brutal, rough, and doesn't paints Joan in a less-than-flattering light, but that's why I love it. If you haven't seen the tv movie, don't bother. It's hammy, melodramatic, and poorly made.
Two I haven't seen mentioned are
Alexander Nevsky (193
and
Krzyzacy (
The Teutonic Knights) (1960). Both are available on Netflix.
Alexander Nevsky (193
is a really well shot, chilling telling of the Teutonic invasion of Novgorod. It's very well made, holds up fairly well, although it's very much so Soviet propaganda. If you don't mind older films, see this movie.
Krzyzacy is a movie I was very impressed by. It's a Polish film from the 1960's, and discusses the events leading up to the Battle of Tannenberg in 1410. It has a nice battle scene at the end, and leading up to it is a very detailed, interesting discussion of the events. It has a nice epic feel, and I quite enjoyed it.