Played as a 1h without shield with 140 wpf. Anything from 120 up is fine, a 100 even. Don't worry about the wpf, what I would worry about is the lower IF you can go because you need high WM and the higher weight and upkeep from carrying another weapon. It's true dat 1h is not great against cav, but just be aware and block lances. Occasionally you can even do ye old jump rightswing and kill a few lancers.
PS is important though if you're using a cut damage weapon, you're going to want atleast 6, preferably 8. Blunt and pierce is fine at any PS.
Wait, what do you mean exactly with a 'pure' 1h if your character has a shield aswell as a polearm?