I ended up going with S/L defense on my DM/FA brute with recharge as a secondary focus. So far so good.
On squishy scrapper secondaries I like Soul Mastery for access to Shadow Meld. If you go this route I recommend clearing ~15% defense to all postitions and types. This will ensure Shadow Meld puts you over the soft cap when activated. Use Shadow Meld proactively in this case.
As far as the lack of AoE goes Burn recently got buffed and is no longer considered a throwaway power. You may get some mileage out of it.
Good Luck with you DM/FA Scrapper!
Burn is an incredible addition now adays. Definitely put that in there with your power picks! 
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Samuel_Tow: Your avatar is... I think I like it
I have a Dark Melee/Fiery Aura in the level 41 range. I enjoy playing him, like the concept, the way he plays, the powersets, the costume. But he is somewhat in the very squishy department (specially compared to my other scrappers). He is fun when he is standing, but every time he drops I just know my other scrappers would have laughed at this.
I'm aware Firey Aura gives defense for damage, and that seems to work fine with more AoE oriented primaries. I don't have problems with Fire/Fire tank, nor do I foresee many with my baby Spines/Fire, but it seems the ST nature of Dark Melee is hurting. (Maybe I should probably up the level of foes instead of how many heroes I'm worth.)
I'm here to see what IO tracks you'd recommend to toughen him up and/or up his damage to a point I'm comfortable with.
Please note:
I know about IOs. My SR and Invul scrapper are defense capped on their own niches. My Fire/Fire tank has proven to be very solid combining recharge, defense, and kill all before they kill you. And I have two almost perma-doms.
I just need an angle or approach that I can see working with this particular build. Everything I can think of have holes in it.
As for expense, maybe in the 300,000,000 range tops, though I'd be getting the fancy recipes with Hero Merits. Purples are out of the question.