Suggestions so far seem to all point towards expansion and militaristic regimes. I have found that small realms are more fun than big ones, yet it seems like small realms will not do good under this system.
How about setting different 'tech trees'? That way, you'd decide wether your realm would be rather army/religion/trade based. Achievements within a same line would provide bigger bonuses. That way, Trader realms like D'Hara would stand a chance, to be glorious realms in their own right, but in a far different way than the classic 'let's expand and beat our neighbours'. It would also provide a sense of continuity.
I should also note that hybrids should be possible. A realm should very well be able to be a bit of everything if they want to. But being the 5th realm on a continent which has a decent military, a few priests and a running trade game should be les glorious than being the top Priest realm, or the strongest military power. Compare it to a class system for realms, if you will.