Tome of Proficiency??

[Ashrem Bayle]

Ok, so I want to introduce a magical book that, when read, gives you proficiency in Martial Weapons.

Now. ...

How much would such a thing cost?

I think a real hole in the magic item creation rules is the lack of specifics when dealing with feats.

 

[Tempuswolf]

As a starting off point, look at how having feat granting ability changes the cost of intelligent magic items...but beyond that I dunno.

 

[CRGreathouse]

Feats, by design, aren't balanced with each other. That makes pricing them with a general formula a bad idea.

In this case I wouldn't charge too much--the classes without martial weapons won't do well in combat even with them. (Of course, one could also say the opposite--it's like getting an unnamed +4 bonus to attack, so it's worth a lot.)

 

[kreynolds]

The Arms and Equipment Guide suggests, as a general guideline for feats that are not represented well by previously existing pricing formulae, 10,000 gp for the feat, plus an additional 5,000 to 10,000 gp per prerequisite.

 

[Spatzimaus]

And that's for an item that gives the Feat as long as it's being used, AFAIK; what you're asking for is the Tome of (insert stat here) that mimic the Wish spell. For that, I'd charge FAR more. Feats shouldn't be dependent on the amount of money you're willing to spend.

"the classes without martial weapons won't do well in combat even with them."

Except Rogues, Monks, and Bards would love this sort of thing.