We all wished to add badges since DotP2013 was out, but it's impossible because there must be something hard-coded into the executable for each supported badge. While it's true that kevlahnota made a custom badge for wither, it has been possible because there was a place for that already, it just had the forestwalk badge as a placeholder.
The best visual aid you can give is to grant the detained permanent a static ability that does nothing except having the text "Detained", if you really want something. I hope DotP2014 will have a new badge at least for "can't block", you can't imagine how many times I made my combat strategies wrong because I forgot that a creature can't block.
