XP cost for Custom Powers/Proficiencies

I have seen three different discussions of Custom Powers/Proficiencies in custom race/class creation.

This post about creating custom races essentially says that a power/proficiency - which are one and the same - costs 40XP:


The Player's Companion p.79 says:

"FIGHTING VALUE TRADE-OFF EXPERIENCE POINT PENALTY A class with a Fighting Value of 2 or greater that makes a tradeoff increases the experience point cost of its Fighting Value by 150XP per custom power gained. This is because once a class has a Fighting Value of 2 or higher, it has so many weapon, armor, and fighting style choices available to it that it can specialize without suffering much loss of effectiveness."

So the cost here is 150XP per power + a loss of some fighter abilities which are traded off for it.

The Player's Companion pp.79-80 allows a direct tradeoff, with no penalty, between Thief Skills and powers, on a one-to-one basis. 3 skills are 200XP; 5 skills are 400XP; 10 skills are 700XP; and 15 skills are 1,100XP, for an average of 72.25XP per Skill/Power.

I am trying to figure out the rationale between these...

1) The "base cost" is 75 XP per class power.

2) Racial powers are intended to be generic to the race, and not directly built to improve the class. For instance, if you're a Spellsword, the fact that you can detect secret doors isn't that helpful to your class. So the XP cost for racial abilities is lowered for that reason. If the racial ability is something that would be universally helpful you can raise the cost to 75 XP.

3) If you are min-maxing a class build that has both fighting abilities and lots of class powers, you can make a much more effective class by taking Fighting 2 and doing trade-offs to narrowly target what you seek to create, than by taking a lower Fighting value and taking points in Thievery. That is a sure sign that the class powers gotten from Fighting 2 are more valuable than those from Thievery. Hence the higher cost.



Thank you for the explanation.