Having reached official old fart stage, and my next birthday being 80 years of age, I've already dealt with this problem. From my own experience and the experience of my friends and neighbors in our senior citizen community who are my age, I can give you this preview;
You won't be doing any wilderness bashing, nor commando operations. What you will need is a small sharp edge to open all those packages with the pull tab that either breaks off or is too much for 79 year old arthritic fingers to deal with. And being retired, I find I do much more fishing with my other retired old fart friends than ever before. A small SAK is a great old fart knife, and most the old farts in our social circle have a classic on them someplace. The scissors are handy as it the little screw driver tip that deals with small flat or Phillips screws.
A small SAK like a 58mm or 74mm fits in with the mostly urban/suburban life you will be living as an old fart. Your backpacking and wilderness tramping days will be far behind you, and you'll spend more time in museums and art galleries than in your younger days. You'll appreciate what your seeing more. A small SAK will be handy for those prepackaged foods like granola bars and such that have plastic wrapping that is designed to defeat senior citizen fingers. And the little scissors are handy for clipping coupons. Living on social security you stretch your pennies as far as you can.
The other thing you will carry is a multitool. Those old fart fingers I told you about? Well, a small pliers will be a VERY handy thing to have on you. Loss of manual dexterity means trouble grasping and dealing with small objects. My Leatherman squirt that I've become addicted to carrying is used, literally, every single day for something. The screw driver is a stronger one than on the small SAK, so its a nice little pry tool. The small flat Phillips makes a great staple puller, (you'll be dealing with tons more paperwork from social security, health insurance companies, and others that like to send out reams of paper often stapled together) and its good for the screws in those glasses you'll be wearing to see anything closer than the end of your arm.
So, at almost 80 years old, my EDC now is a small SAK and a Leatherman squirt. If I need more knife than that, I will use a small fixed blade. Much easier to deal with, no opening, no closing, no worry about hidden areas for dirt and bacteria. My wife carried one of those Victorinox serrated edge paring knives with the matching red plastic blade cover, in her purse. It's our food and dirty deeds knife when traveling on one of the cross country car trips we take to see family in California and back in Maryland. Or Big Bend, or Grand Canyon, or Mesa Verde or whatever. That Victorinox cuts through most anything. Being a cheap, excuse me, low cost knife, it gets the abuse but it still keeps on going.
Forget the larger single blade locking stuff, its just too big for the pocket. Your pockets will be filled with other stuff like spare glasses, meds for arthritis and any other medical condition that you will develop. Then theres the small magnifying glass because sometimes they print stuff designed to be unreadable by senior citizens. You'll need it. Then theres the spare bandana you'll need. and the small flashlight because your night vision has gone to hell, and the little flashlight helps you find that pill you dropped on the tile bathroom floor and it rolled away. By getting down and shinning the light out across the floor from floor lever, the small pill or whatever you dropped will stand out like a boulder on a flat plain.
Then theres the small bottle of hand sanitizer. Being mostly fast evaporating alcohol, its handy for cleaning small spills and stains on clothing. Old people tend to drop stuff and fumble food, and spills WILL happen. Hand sanitizer is a great instant cleanup that dries in a few minute and that stain you your shirt is gone.
And being a feeble old fart, no longer able to fight much, your daily CCW carry will be in a pocket. Never try to fight an old man, he'll just shoot ya. Spare ammo will take up some more room. And then the RONCO pocket defibrillator in case of a serious vapor lock.
Soooo, forget about that large lock blade. You simply won't have room in your pocket for much over the size of a SAK classic. If this sounds a bit depressing, that is old age folks. Life gets harder the other size of 70, but the alternative is way worse. I'm guessing the grass looks like hell from the underside, so we keep on going the best we can. And trust me, knives will shrink in importance the older you get. As your time gets way shorter, inanimate cult worship objects vastly shrink in how important they are, compared to the people in your life, and to keep going to enjoy every minute you have left. I look back on the knife obsession and wonder what the hell was I thinking???? A good car under you and a AAA membership is way more important than some knife in a pocket. Any little easy to open sharp bit of steel will do and if it has a few tools on it for poking and light prying and screw driving, so much the better.
Old age ain't for the faint of heart! You're gonna have so much more to deal with, you won't care about what knife is in your pocket.
