I tend to agree with 'mdsmith' I picked one up at a local big box store for unde $10, it uses replaceable double ended razor blades, and if you lose it, well, no big deal, as you lost the equivalent of lunch money.
Save your knife blades, and use the disposable /replaceable option.
I mean if the main goal is opening boxes, then I wouldn't concern myself with aesthetics or "pocket carry" as it would be a tool to just open boxes.-and at $10 bucks or so-I'd leave it where I needed it..not carry it.
Just my .02.