I agree with using a box end wrench to tighten the nut, you'll never get the nut tighten enough with those 4-way wrenches. But I would add another piece of advice to that. Wear a leather glove on the hand that you are holding the prop with. I learned this when I had the sharp edge of a Master Airscrew prop make a really nice slice into my hand. If you wear a glove you can get it tight enough without hurting your hand.

Hope this helps