Saeviomagy
Adventurer
A Dex mod of 11 is not only unlikely, it's impossible. Starting with an 18, +2 from race, +2 from Demigod, +2 in heroic, +3 in paragon, +3 in epic = 30, for a mod of +10 at level 28. That is currently the highest you can possibly get any single score in the game. So I guess bloodiron is the way to go![]()
You forgot the extra +2 from the DMs custom, homebrew ultimate rogue race

And yes, bloodiron is the way to go if you don't care about when the damage occurs.
As for avoiding the d4? If you feel that strongly, pick up a kukri: +2/d6, brutal 1, counts as a dagger (technically only for rogue weapon talent, but I doubt any DM would begrudge you this).