Have you considered a multi-tool? Seems like some pliers based multi-would cover a lot of ground, like having side cutters, scissors, a fire, a knife, often a serrated knife too, and so on. There are some one-have open options as well if you wants quicker deployment of the pliers and cutter but usually the rest of the tools are more hidden, at least on the one-hand-openers I've tried.
Something like a rebar or wingman seems like it would be good.
For much of those task, I really like a hawkbill but those are not as easy to sharpen. If you mostly want something for boxes, pretty much anything thin-ish and that has a reasonable amount of straight edge, like a sheepsfoot blade. I would also recommend a larger grip and non-metal scales so it doesn't slide around with dirty hands if he uses it for everything. Beyond that, I think he would probably be happy with anything better than what he has if he only has "junk" knives.
I like the CS tuff lite recommendation.