I'm going on my fourth Grandmaster and the only way I have found to get other blades is from Kroktopia, Niles the tree next to the Balance school has 2 sets of elemental blades you can train for and 2 sets of elelmental shields.
You can't learn other school's blades, besides the elemental and spirit blades of the balance school. I haven't tried personally, but I'd imagine it's possible to make blade treasure cards with keen eyes to give to other people.
Yes and no. You can get the blades from the Balance tree in Krokotopia at level 25 but you would have to use skills points to get them and you would need to get the traps before you can get the blades. Unless you are balance than you dont need to spend any skill points for them. Other than that you cant learn them any other place.
My question is basic. Can I learn other classes blade's? If so, where do I learn them?
no, you cannot, unless you have enough traing points to learn spirit blade or elemental blade. spirit blade gives you plus 35 % to your next death, life, and myth spells. elemental blade gives you plus 35% to you next fire, storm, and ice spells. you can get those spells form Nlies the Balance Tree at the Kroksphinx in Krokotopia.
I checked the Wizard 101 wiki, and as far as I know the blades are pretty much only for your primary. However, you can buy elemental blade (ice/fire/storm) and spirit blade (myth/life/death) from the Balance Tree in Krokotopia. Each of those spells will cast 3 +35% blades, one of each of the types they cover. However, rather than being a zero pip spell, it is a one pip spell, so it isn't really useful for building up pips. Also, neither of those 2 spells needs previous spells in the school to learn, and there is also a trap version of those 2 spells as well (elemental trap and spirit trap). I hope that helps.