I did an experiment on my current Paladin build to see whether I could get my stunning blow DC high enough to be reliable up through epic hard quests, and it works! Before the change to divine might being a bonus to strength, I could never get my combat tactics DCs high enough, but with the change I found it is now possible! My character is finally level 28, and I've tested Stunning Blow on most quests throughout the leveling process (running heroic elites and epic hards), and it has been an invaluable feat and a great way to increase DPS. For anyone not familiar with stunning blow, when you get it to land successfully the target will take 50% extra damage for 6 seconds, which is huge for a Paladin normally short on DPS. Also, I realize that in EE the DC requirement will be too high, but I'm happy running in EH. If someone wants to play a Paladin up through epic hards and not epic elites, I would recommend considering to add stunning blow into your build. For full disclosure, my character is a TR x2, so I have a 36 point build and +5 tomes in strength and charisma, but I haven't bothered with fighter past lives, or tried to max out all of my gear, so if someone works at it, I would think epic hards should be in reach.
Below are some tips I found from other forums posters, as well as my own experience on how to get a meaningful DC. In no particular order:
-You need to max strength out to get the highest DC and DPS possible.
-I recommend a starting strength of 16 on any Paladin (even a fresh 28 point build), though you could go with 18 if you're a 2X TR with lots of tomes. All/most of your level ups should go to strength. Even so, I started at 16 so I had points for other stats.
-The change to Divine Might has been super helpful to achieve a higher strength! Thank you Devs for this Without this change, I don't think stunning blow would have been viable
-Go S&B so you can take the +6 to strength enhancement. Again, you need as much strength as you can get.
-You can use Cannith Crafting to craft a shield with the stunning suffix (up to +8). If you can do some crafting, this is an easy way to get a stunning blow DC increase, while still letting you keep your primary weapon a DPS weapon. I don't like using a stunning weapon in my primary hand, because it's a pain to swap weapons all the time.
-Run the Cannith challenges to pick up the Spare Hand belt for exceptional combat mastery (up to +5).
-Take a 2 Fighter splash. This not only grants haste boost, tower shield for free, and 2 feats, but it grants access to the combat tactics enhancement in Kensai. I generally have been running with tier 2 or 3. It is a very expensive enhancement, but it is helpful.
-Use Legendary Tactics in the Legendary Dreadnaught epic destiny (either while in LD, or as a twist), for +6 to your DCs.
-Improved Sunder...I found this pretty helpful at times, while leveling up and working on improving my DCs. Essentially it gives an opponent a -3 to fort saves, even if they make their save, which means a +3 to your stunning blow DC. I would use this when I wasn't reliably landing stunning blow. At max level, with lots of good gear and a good strength I rarely use this any more, but it was helpful while leveling up.
-Wounding / Puncturing: Only once in a while would I use this trick. A wounding and/or puncturing weapon will lower a mobs con and thus their fort save. I found this helpful sometimes against orange named werewolves in Eveningstar, and giants in the Stormhorns to soften up their save first. For those mobs where a stunning blow wouldn't land normally (even with improved sunder), softening them up with a wounding of puncturing rapier (which is craftable) worked pretty nicely.
-Trip: Without even working on it, I found my trip (regular trip that you get for free) works pretty well and is a nice little bonus.
Edit: Forgot about the epic destiny feat "tactician". That's another easy 2 pts to your DC at level 26
In any event, I just wanted to share my experience with anyone playing or wanting to play a Paladin out there. I hope this helps