Meteor, Blizzard and Bolting in Chapters 17 and 18 (Path of Radiance)

Solution 1:

The long-ranged tomes are stealable.

Mages can only use Meteor/Blizzard/Bolting if there are units from 3 to 10 spaces afar from him. That is, if their only targets are at the range of 1-2 spaces, they will switch tones.

Meteor

With a flier, drop a thief next to the mage. Evacuate everybody else from the mage's targeting range. He will be forced to switch to Fire, unequipping Meteor for you to steal.

You have to do this in the very turn the flier crosses the woods, otherwise, Tibarn's squad will arrive and the mage will use Meteor on them. You also have to kill the soldier next to him with a ranged unit beforehand. A suggestion is to shove a reasonably-leveled Rolf multiple times, then save him with a mounted united in the following turns.

Bolting

Place four units in a cross formation and make heron Reyson sing at the center. With rescue, up to seven units can join him. For Shinon to be recruited, Rolf and Ike must be included. If you want to steal Blizzard later on, add at least two mounted units. Three (being one promoted) and both thieves, are recommended to steal Elixir and get Tornado with most uses.

Now, approach the sage. If there are rescued units, drop them. Don't block the path between Rolf and Shinon, otherwise, the latter will attack.

Defeat everyone but the sage, advance Reyson and form a triangle with your units. This leaves the sage with only one option: Thunder. Steal Bolting and you're done.

Blizzard

Cross formation with Reyson in the center again. Thief at north, promoted horse with thief at east, horse at west and horse at south.

Now, kill one enemy horseman blocking the path, and place the units as it follows. Evacuate everybody else, including Reyson (by rescuing him). Now, the sage can only use Wind. Steal Blizzard and Elixir and kill Kayachey. Congratulations! You got all three long-ranged tomes!