This topic is my biggest hurdle for my EDC manbag.  I have some gear that I love, but it's bigger and heavier than other gear that will get the job done adequately.  For example, I love my Fenix LD10, but my Fenix LD15 will get the job done most of the time and it's twice as small.  However, I have decided to carry my Fenix LD10 in my EDC manbag.  A flashlight and a whistle are two things I've decided don't need to be the smallest things on the market.
I'll compromise on everything else if I must.  For example, instead of carrying a P51 can opener, I'll carry a P38 or none at all.  Instead of a large Widgy, I'll carry a Pic Widgy or none at all.  Instead of carrying a spare AA battery and case, I'll carry a fauxton light or none at all.  Instead of carrying a bandana, I'll make sure my knife can cut my T-shirt.  You get the idea...
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If you're reading this, it's too late.