Ok, here is another question.
For item triggers, I can display a stat on the item by using this:
<stat:kingslayercount>
When I attempt to utilize the same method for a skill, it does not reveal the stat amount. It just says <stat:kingslayercount> in the skill description. Any ideas?
Wow I keep putting my posts in the wrong area. Oh well.
I'd use the ADDITIONAL DESCRIPTION field (it's part of the ADD AFFIX properties in the Skill Editor). I think it might overwrite the display of the effects contained in your affix, and you'll have to modify it manually per level, but you can make it say whatever you want.
Doing as you suggest results in the same problem. It still just displays <stat:kingslayercount> in the description.
I think this is a limitation on the way the UI is handled to be honest. I hit the same problem trying to display a stat in a quest description in the same way you describe.
It seems that certain elements of the UI recognise <stat:> as a tag where the UI widget is an internal name but, in general, the simple text display ones do not - this appears to be hardwired

To achieve your effect, you'd have to somehow overwrite the relevant element with your information in the UI layout.
Hey Epoch,
Instead of
<STRING>ADDITIONALTEXT:<stat:kinslayercount>
I'm suggesting
<STRING>ADDITIONALTEXT: +1 to Kinslayer
But if you want a dynamic stat in there, then you'll probably have to modify the Equipment Mouseover UI. I'm 100% positive you can add it to the UI element.
Just copy and paste the stat display for things like "Slay 100 Dwarves" and use your stats instead. Then, add a statevaluator that starts when the UI piece is displayed (I think it's either MenuController or UIController (and use the 'Initiated' input)). Make the statevaluator: Kinslayer > 0: Show, Kinslayer<1: Hide (where it's showing/hiding the text display).