The rotring 800 0.5mm pencil has been a workhorse for me. My conditions were that it can handle being carried at all times and not stab me in the leg.

It's even survived going through clothes washing machine. The one part I had some minor annoyance with is the ring below the control to adjust tip retraction would loosen up when carried awhile. I originally used a bit of superglue which came out in the wash. Now I've added some loctite so it will probably never loosen again. Other than some finish wearing off it's been great for years.

Edit: oh I use pilot neox F graphite in it. Feels like writing with HB but it doesn't break as easy as I write with pretty heavy hands.