I tighten my pinned knives using a vice or, in a pinch, a pair of vice-grips or knipex plier-wrenches. The knipex tool leaves less marking, if any. In a vice, is smooth metal to cover the jaws.
Once tight, a nail or such can be used to peen the ends of the pin.
Caution as to over-tightening. Tighten a bit at a time, till the knife opens like you want.