A stronger person will be able to get an edged weapon to penetrate deeper into their target, even cutting through bone, or carry a cut further through the skin, causing more blood loss. They'd also potentially be able to smash through a defence, causing light injuries where a weaker person wouldn't be able to.
A stronger person would also be able to wield a heavier weapon, so you could potentially start multiplying the effects of higher strength - although you could then get into issues based around their own momentum.
To an extent, but there's a lot of difference in how far you'll got through if you just drop the cleaver on it from an inch above, or bring it down with a reasonable amount of strength from six inches above.
And for a stronger person, there's more potentially fatal areas available to them - some of which may have bone in the way.On a human body I'd say that anyone can stab a knife deep enough to make it fatal, unless there's bone in the way.
Depending of course where the knife hits.