In case someone hasn't answered this already...

X-Perl does in fact show runes just fine. You guys are lazy. The problem is when you play a DK it doesn't automatically SELECT the "show runes" option. Open your x-perl menu, go to the "Player" tab, and check the box to Show Runes :P

It took me all of about 5 seconds to check and see that this wasn't selected and then select it.