Good question, presupposing the general perception of aikido as a "peaceful" martial art, and the general
perception of weapons as tools of war.

The founder Morihei Ueshiba, who we call O-Sensei, was passionate about weapons practice.  The use of
weapons in aikido was essential to him.  Perhaps it is easiest to explain why weapons remain a large part
of training even today is to point directly at Japanese culture and history.  If we were looking at American
native culture, maybe we'd be practicing a martial art that used principles of archery or knife work.  But the
Japanese clearly had a sword based cultural mythos, which has carried over into many of the koryu
(traditional martial arts).  O-Sensei focused on the sword and the short staff.

The more practical answer for why we practice with weapons is that the concepts in aikido hold true
whether you are empty handed or whether you have a bokken or jo in your hands.  Balance, centering, ki
extension, zanshin, ma-ai:  these are all concepts that apply across the board.  In some ways, it becomes
easier for the ego to absorb these concepts with a weapon in hand.  Suburi with the ken helps your body
learn about dropping the hips, for example.  Without that practice, the ego may never come to understand
what "dropping the hips" means.
Why practice weapons outside?

There are so many reasons to practice outside, its difficult to know where to begin.

Outside, you don't have to worry about breaking the light fixtures or knocking the picture of
O-sensei off the shomen.  The generally expansive movements of the jo, for instance, are well
suited for large areas.  On the mat one has to constantly worry about hitting someone or

Outdoor training is primal, ancient, prototypal, archetypal.  Consider the generations of humans
that have practiced warrior arts under the sky, in dusty clearings surrounded by ancient trees.  
There is some genetic memory that awakens in those circumstances, which makes you realize
that there's a reason it's done.  The first time you hold a sword, cutting towards the rising sun,
heart pounding from hard training-- you feel connected to an ancient tradition.

Another reason is simply TO GET OUTSIDE.  Consider how much time the average American
spends outside.  Time spent driving doesn't count.  We spend our lives entirely too insulated
from the real world of the elements, and as path, aikido is about harmonizing with the energy of
the universe.  Stepping outside the safety, comfort, luxury, and predictability of everyday climate
controlled existence, we train outside to really experience the multifaceted energy of the

When you've spent an hour and a half training in the rain, the child in you is ecstatic.  Do you
remember when you were a kid and you looked forward to going out and playing in the rain?  Or
even better: playing in the snow!  Outdoor training gives you a hardcore martial arts warrior
excuse to "go outside and play!"  You get to get all muddy and sweaty!

People go jogging in all weather, don't they?  It's probably the same reason why people go
running outside instead of running on a treadmill in a climate controlled gym in front of the TV!  
In reality, if we are practicing a martial art, learning to use swords and staves for protecting our
families-- where do you suspect you'll use it?  In a well lighted, climate controlled setting?
Why Weapons?