This isn't about magic combat tricks, just combat tricks.
Looking over the list of combat tricks it strikes me that these seem to be options that anyone could do without special training. I don't think that they should have to be purchased with experience. Also, I think the attribute prerequisites are unnecessary coupled with cost. For example, 'Knockdown': STR 5+ & 2 dice cost. With a cost of 2 dice that already eliminates anyone with an attribute of three or less. STR 4 has three dice in their pool just like STR 5 so it seems a little odd to set the prerequisite at five. The cost is going to limit spellcasters with fairly low physical attributes from attempting these without magical enhancement.
As you say, spellcasters are well served in terms of options. I'd like to see a more open system for the fighting types. I was really excited when Pathfinder came out with Combat Maneuver Bonus/Defense. It seemed like an easy, elegant system and I couldn't wait to try it. Then they layered on feat after feat so that they only people who really use them are those who specialize; everyone else just swings, applies damage, and CMB/CMD goes largely unused. I really like the more open system of Mighty Deeds that Dungeon Crawl Classics RPG uses.
So, I would probably remove XP cost and prerequisites and give everything a dice cost. Then when attempting the maneuver take the dice cost from the attacking dice pool and replace them with either different colored dice or different size dice (e.g. d4 instead of d6) to differentiate from the attack pool. Roll 'em all. If the attack misses, maneuver fails. If the attack hits, then check the maneuver pool: to determine success the dice need to have a certain number or within a range of numbers on the dice face or meet a target number to succeed.
I think a system like this fits better with the open skills and wide options of spellcasting than a limited system of buying individual tricks does. As for ambidexterity, I'd greatly decrease its bonus and make it a AGI trait.