You want to be cautious about applying conditioner to the leather. You start rubbing, and next thing you know the leather starts shredding and you have a hole where a strop used to be. Just apply lightly, wait 24 hours and do it again. Pure Neatsfoot oil is probably the best to use, though any leather conditioner will work. As for abrasive, a dab or two of automotive rubbing compound rubbed into the leather will work. It doesn't need to be anything highly abrasive, just enough to remove any oxidation from the edge. It's about half as abrasive as strop dressing. Those diamond or CBN nano sprays would work too, but you would need to order those, and most people have rubbing compound laying around their garage or shop.
That might work for the old thick 3 hole blades. You'll be lucky to get 30-40 shaves from a modern blade.
That's probably good enough. Looks like it's a bit more abrasive than the turtle wax stuff I used. Which may give better results. I would try it without the compound first, and only start using that if you don't like the results you get from just plain leather. You can always add, but taking away once added is more complicated. Edit: I would definitely put a little on a rag, and rub the blade surface to see what kind of shine it leaves. You want to look for scratches left by the compound. You don't want to see any.
