The
Law of Large Numbers says otherwise. On average, the Khopesh will out-DPS the Rapier. Saying that it's possible for the Khopesh-user to roll 20 1s in a row and therefore the Rapier-user will out-DPS the Khopesh-user during that period doesn't mean anything since all of those situations are accounted for, including the Rapier-user rolling 20 1s in a row, and so on.
Heavy Picks are bad for Paladins, as are Dwarven Axes.
D-Axes being worse should be obvious, as they are only 19-20 3x, while a Khopesh is 17-20 3x. The minor increase of damage dice for D-Axe doesn't make up for the larger crit range of a Khopesh.
Heavy Pics are worse because, in addition to being a crit power 6 weapon (Khopesh is 8), Heavy Picks have lower base damage than Khopeshes. The exception is auto-crit situations.
For comparison:
Holy Sword (Heavy Pick):
.95 * 3.5 * 2 + .85 * (3.5 + 5 + 12 + 3 + 8 + 5) + .1 * 4 * (3.5 + 5 + 12 + 3 + 8 + 5 + 6) + .1 * 3.5 * 5
6.65 + 31.025 + 17 + 1.75
56.425
Honestly, Heavy Picks are behind rapiers.
Diehard and Force of Personality are both worthless for a Paladin.
Diehard only works when you have -9 to 0 hitpoints. It's useless for a Warforged (since they don't bleed), and you can wear a Mantle of the Worldshaper to get a hitpoint back on a fleshie, which stops you from bleeding.
As for Force of Personality, Paladins already get CHA to saves. FoP will just put your Will Save (which is the least important save) into the level of "only fail on a 1", which you probably already are anyway. On top of that, you can be immune to so many things that have Will saves. Honestly, FoP is a waste on a Paladin.
You should be. It can bypass raid boss DR in the hands of a Paladin, and deals more damage than a Mineral 2 (which in turn deals more damage than a Holy Sword).