Spells without Wands

[Matthew Buffington]

No: HPFGUIDX 138550

After reading HBP I was very happy to receive and explanation about 
nonverbal spells. I had always suspected that verbal incantations
were not necessary for spells, but it felt good to have a clear
explanation on the subject (and that the students were actually 
taught it). 

However, I am still slightly confused about the use of spells 
without wands. In SS, Harry causes several magical things to happen 
without the use of a wand. Even Quirrel makes ropes jump out of no 
where to tie Harry up, seemingly without the use of a wand. Likewise 
in PoA, Harry doesn't use a wand to make his Aunt Marge blow up into 
a balloon.

Now, I know that magically inclined individuals can make things
happen without wands because they are upset or afraid. But, wouldn't 
it be reasonable that a very talented wizard or witch could train
themselves to learn how to do spells without their wands? If it is 
possible to cast spells without a wand when emotional, couldn't one 
channel those emotions to produce spells whenever they wanted? 

Which then comes to my real point, if DD was so powerful, why does 
being wandless leave him so vulnerable? (This is assuming that he 
didn't have a plan to die or appear to die) I can also think of a 
several other reasons why it would be useful to use spells without 
wands. We know it is possible, so why can't powerful individuals 
channel that power whenever they wish.

Being new to the group and the whole HP world, I would love to hear 
some theories about this issue. 

Mattcbuff