Hickory: No. Your arcane and divine spell books are completely separate, and are governed by different stats. Arcane spells, and the
amount you can learn per level, are governed by your character's INT -- at 19 INT there is no limit -- whereas divine spells, governed by WIS, are not learned but
granted automatically every turn. The higher your character's WIS the better, because bonus slots are granted as WIS gets higher.
SerWind: I guess what I meant was naturally I'll end up being a higher level mage if I just go pure mage and thus get more slots for mage spells in the end, right?
Also what does it mean to have no limit on the amount you can learn per level if you have 19 int? I've always been a little confused about that.
What he means is this...
At each spell level, there are around 20 spells, some levels have more spells, some have less. If a Mage's intelligence is 19, he can learn every scroll he comes across in the game. Otherwise there is a limit on the number of spells he can scribe in the spellbook for each level of spells.
Int -------> Spells
18-------> 17
17-------> 14
16-------> 11
Oh and yes a pure class mage or cleric will gain access to higher level spells quicker compared to a multi-class mage or cleric. It is not so noticeable in BG 1, but in BG 2 my multi-class characters are significantly behind the specialists in terms of spells.
The problem is mitigated somewhat in the long run with Dual-classing, where depending on when you make the switch, a dual-class character can almost catch up to a specialist. For example Anomen in BG 2 is not much worse than a specialist Cleric, but Aerie, being multi-class, is quite some way behind him and Viconia, who is a specialist Cleric.
KiNgBrAdLeY7: You can always roll a Berserker Mage, instead. Why loose on the gauntlets of extraordinary specialization, or the berserking temporary immunities, by having to waste precious spell slots? I do not know your playstyle, just a suggestion it is. I had a fighter through 1, in my previous playthrough, got him to 2, and dualled him at 10 level. You can at 9, if you wish, instead. By the end of Tob, i had grandmastery to Quarterstaff and 2handed sword, specialization in 2 handed weapons, and a proficiency in darts, just because i had to spend 1* to something.
In SoA, the Staff of the magi and the Silver sword, worked actually pretty well on him. In tob, i made circlet of netheril, improved cloak of protection +2, Staff of the Ram and Gram the Sword of Grief. Robes of Vecna and amulet of power; i couldn't find the motivation to change them with something else, new! Belt of inertial barrier. Rings, gaxx and wizardry (2 gaxx, if you pickpocket him carefully before killing, which i did).
Kensai is best to dual to thief, i believe. Use any item, plus thieving skills to avoid becoming early target for control/crowd control spells/abilities, cry out for this combination. Those who use kensai mages, mostly advice for dual wield and exotic weaponry, like katanas (magic katanas from special vendor also allow you to cast more spells), yet the true trademark weapon of the warrior is the 2H sword, and of the mage the Staff. Nuff said. Some claim berserker to mage is absurd and makes no sense lore and rp wise. But you have to try it. It is very fun.
If by any chance you still need to Kensai->Mage that desperately, you do it at 9 for good timing, at 13 for best (but this way you will need lots of xp to reactivate old class). Another reason that Kensai->Thief is a better idea overall. Because you can dual at 13 and still reach thief max level minus only 1.
You should know by now that I am completely opposite to you as a player. Powergaming does not appeal to me in the slightest. Cheesing actually annoys me, and you cheese on such a level that I feel like something criminal has been committed against this great game.