Just use your knife in a normal fashion, and be able to clearly explain things if asked.
To the "SAK is fine!" crowd...no, that doesn't always work on its own either.
As I presented the groomsmen gifts of Victorinox Sport model Swiss Army Knives for my brother's wedding, a couple of the bridesmaids said "Knives? As a present?!? Why knives?"
Utter confusion at the concept...
But I was able to clearly articulate, in a calm fashion the various non-ninja uses of such things, and they then got it.
And it isn't just because they're girls, because one of the other bridesmaids owns her own knives, and thought the Cold Steel Large Espada with polished G-10 scales and aluminum frame/bolsters was cool

(that was at a wedding favour stuffing event I got suckered into...at which two
men went completely silent at the presence of the ZT 0561, and wouldn't look in my direction until it was closed; go figure).
The point is, calmly explain things, use them in a normal fashion, and if people still have a problem, then
they're the ones with a problem.