What an excellent idea! Here's My humble opinion. I dont think I would add anything to your card design. You covered all the bases quite well IMO. If anything I would take away from it. Since space is at a premium he's my opinon on which items are least important and could be done without it needed.

-Magnesium bar going down the length of one side, as thick as the card - Excellent
-Ferrocium rod going down the length of the other - Excellent
-Signal Mirror on Top (pull out or part of the top? Not sure) - Excellent
-Diamond Knife Sharpener on bottom (maybe a small pull out or part of the bottom itself? not sure) - Excellent
-Fresnel Lens sandwiched in between (pull out type) - Moderate
-Maybe a Tinder Card sandwiched in between, if it fits (pull out) - Less than moderate (redundant)
-Good strong knife (like the tool logic ones, rather than the swisscard ones) - Excellent
-Small pen for writing - Less than moderate
-Toothpick - Less than moderate
-Straight pen - Less than moderate
-Pull out LED - Excellent
-Maybe a small compartment for matches, hooks/line or one or two purification tablets or something - Excellent

Okay I might add one thing. A whistle. Toologic has incorporates whistles in to their knife handles in a way that could easily be done with a small plastic card as well.