Level 51 in a month... Well, I'm lvl 55(took me 6 months grr), and the 2 spells I quested for were Divine might, and Etheral Cleansing. I use both spells all the time. Both are soloable.
-Divine Might is quite tedious, with alot of running around, but its worth the trouble I say. It procs 65pts to all mobs except well resited ones, but it procs often and more so if your Dexterity is high. Look up this spell on your spell list for tons of good info.
-Etheral Cleansing is worth the time, and at 52 it should be a cake walk unless your toon has low skills. I do reccomend this spell, it always stays in my spell line-up for the fast casting and the 100hp for 5 ticks (500pts). The quest takes place in The Gulf of Gunthak, and Dulak's Harbor. Again, look up the info on your spell list, too much for me to type at the moment.
I have all my spells, but I don't use half of them in most cases. They all have there place, but most are pretty useless due to the high mana cost to damage/ stun/ heal out come ratio.
Some spell have to be dropped of mobs like Flame of Light, but if you feel like getting ripped off, go to the Bazzar. To me , those ones are worth you time:)