Okay here is the rule in question:
Broad study (ex): A magus with this magus arcana must select one other class that grants the ability to cast spells.The magus can use his spellstrike and spell combat abilities while casting or using spells from the spell list of that class. This does not allow him to cast arcane spells from that classes spell list without suffering the normal chances of arcane spell failure. the magus must be at least 6th level before selecting this arcana.
I see some issues with the wording of this feature other than some ambiguity with the level of magus to qualify for the ability. From the way it is written the ability requires the player to select a different caster class to apply this ability. It doesn't say that you must already have the class to apply the feature to, only that you must take one. (This has been addressed earlier in the thread).
I see the problem as being poor choice of words, although it is described in a subsection of a class feature the lack of precise wording leaves one to assume, wrongly, that the player is entitled to use abilities that they do not actually have.
Because of this I can see where someone could interpret the rule as implying something it was never intended to. As for the question of whether it can be taken at a certain level, either at the indicated class level or character level, it is ambiguous enough to cause some people to misinterpret the intent.
From what I can see, the entire class feature is so limited in it's application that there is little benefit from using it. Broad study allows the use of a questionable ability (ie spellstrike) to use spells from another caster class along with their own spells, but restricts metamagic feats to one time a day. It seems like a collection of disperate abilities whose power is widely inconsistent are cobbled together to give the class something to fill out it's class progression. Giving the impression that the character is getting a nice ability then limiting it to the point where it is nearly useless. Take critical strike for example. Anytime you score a critical hit... this can be used one time a day. and then requiring you to be 12th level to use it that one time a day.
At first blush the class was a good idea. Combining fighter and mage together in one class would be something I would like to play, but the magus really doesn't do much toward this end, rather it seems that the class is trying to give a spell caster a sword to use as a wand.
I hope the rest of the book has something useful in it. As far as I am concerned this class is a waste of paper.
