Wisdom has a direct bearing on two important, and one not so important thing. Like intelligence, wisdom has an effect on your mana gain. So, if mana is important to you (and it should be if you use spells) then you probably want to have a high wisdom. Although you can handle wisdom with equipment, much like intelligence, it's probably in your best interest to put trains into wisdom before intelligence. Because of ...

... saves. Wisdom also gives you bonuses (or penalties) to your save vs spell count. Because SVS becomes very important at hero, you typically want to get as much SVS as possible (Remember, the more negative SVS you get, the better your chances of resisting a spell's effect or taking less damage) through natural means before having to make equipment choices. In the end, it's better to have a higher natural wisdom then intelligence because of SVS.

Of minor note, wisdom apparently grants some resistance against illusions. What this actually means is that you probably take less damage per attack from an illusion. There's a lot of "probably" here because an air scholar with illusions is somewhat of a rare occurrence at the time of this writing. In the end, as a scholar, it's probably better to sink more trains into wisdom then intelligence, and then use equipment to cover the hole left behind in your intelligence stat. However, intelligence does bear a lot of weight in terms of roleplaying (don't play smart characters if you have a low intelligence), so it's still in your interest to train the stat anyway. Everyone else can train wisdom at their choice, just remember that extra SVS is ALWAYS useful.

Dexterity

Dexterity is probably the make or break stat of the skill sets. It's either extremely important to you, or it's extremely useless. The rule of thumb is this: If you have dodge for a skill, you want max dexterity. More dexterity means better chance of dodging, better dodging means longer in combat. Dexterity effects a few other things, but nothing that's heavily important. There are however, exceptions.

Dexterity is one of those main stats (next to strength) that comes into play when considering defense against a skill (dodging an impale/garrote/etc). So, if you're one of those people who hates to get garroted, you may want to put some consideration into dexterity.

Just to cover all the bases however, dexterity also adds hitroll. However, there's a heavy diminishing returns when it comes to hitroll, I've played warriors with as little hitroll as 20-30 (and much less, if I'm a scholar) without having any problems hitting my attackers. There was once a rumor that higher hitroll allows for better chances of breaking through opponent parry and dodge rates, but this has never been confirmed or denied. But honestly, you should never train dexterity for extra hitroll. You'll gain more than enough via equipment.

Dexterity also effects how many items you can carry. This is pretty negligent, considering the base number is already more than enough for the average player. If you find you're having problems though, just use a container to consolidate space.

Dexterity also grants AC bonuses. For every point of dexterity above 14, you will gain a 10 AC bonus. This isn't very important though, as spells such as armor and shield can grant you 40 AC points to begin with, and equipment alone should knock you into a safe region for AC. AC is pretty negligent in itself, but that's a story for another day. (Short story: AC is widely believed as useless past level 20, and almost nobody chooses equipment based on AC values).

To summarize then, if you're capable of dodging, you want as much dexterity as possible. Otherwise, the only reason you want dexterity is for defense against certain skills.