You do know that there are grenades in DDO right?
Not to mention throwing in most every system I've played was governed by strength.
That's why I figure an almost pure rogue(or a small fighter splash) for a special forces type soldier,you get free repeaters and the ability to play with the stinks and bangs without being an actual arcane.
Also,where did I say anything about not taking DD in my vision of a modern soldier rogue,most folks I met were pretty handy to have around when something needed fixing (or breaking for that matter).
It'd be basically playing a technically proficient firebug,sounds like a fun to me.
I suggested skill focus:umd just so you can get up to no-fail heal scrolls easier and you have more than enough spare feats for it.
If you don't feel like you need a 39 umd that's on you,but it'd be a big help and step towards healing in later game content when your wand whipping just won't cut it.
Really,have you thought about going elf for AA?
Maybe switch things around so you use a bow,between manyshot and sneak attack you should put out some kind of nice damage.
On a side note,how exactly are those two extra toughness helping your dps?