My GM and I are having a bit of a debate about what those prestige classes that add "+1 level of existing class" actually do when in it comes to base class abilities that have a level scaling component.
The rule text of contention, taken from the Arcane Trickster in this case, reads as follows.
She does not, however, gain other benefits a character of that class would have gained, except for additional spells per day, spells known (if she is a spontaneous spellcaster), and an increased effective level of spellcasting.
This seems straightforward enough, but then I noticed that some abilities that one can acquire as an arcane class have level scaling components to them.
I shall provide two examples that I came across, though I am sure there are plenty more.
The first is the Arcanist exploit "Arcane Weapon.") It allows you to enchant a weapon to have a +1 bonus and higher as you gain levels, and you are allowed to add various effects that total up to your maximum allowed bonus based upon your level.
Another case is the Sorcerer's Arcane Bloodline and their third level Metamagic Adept power, which is supposed to increase in number of uses with increasing sorcerer caster level.
Off of common sense and the presumed spirit of the rules, I would think that something you knew how to do before you started going down the trickster's path, something that was presumably tied to your ability as a spellcaster in general (thus the level scaling) would continue to improve, even if you learned nothing new from your first paths beyond that point. A 13th level spell caster (assuming a 3rd level arcanist/10th level trickster) presumably could enhance their weapon better than they could when they started off earlier.
On the other, there is no explicit rule that I can find one way or the other on this aspect of the prestige class spellcasting abilities increase, and my GM is a bit a concerned about the possibility of balance issues.
In essence, does "an increased effective level of spellcasting" necessitate treating any level scaling ability from a base caster class as though you were an appropriate level caster for said ability? E.g., if you cast arcanist spells at 13th level, does your level-scaling exploit also cast at 13th?
Thanks for any and all edification on the topic.