Is Weapon supposed to be evil? I thougt that Weapon was supposed to protect the planet from harm but it doesn't look like it. Would the planet create omething to kill it self I don't thing so.

I think it would...

People kill themselfs in situations like that all the time...

But Weapon was to destroy Jenova.

From what I can remember, and from what I can interpret from the storyline (which may be different to other people's interpretation), Weapon wasn't truly evil.

Weapon was released by the planet, because the planet itself was in danger (from Meteor and Sephiroth, etc.) Weapon was meant to be there to protect the planet, by locating the source of the danger and eliminating it. (You remember when the Weapon that fought you outside Midgar turned away as the Mako Cannon was to be fired at the Northern Crater, causing the death of a lot of the lifestream, in order to counter that threat, thus trying to protect the planet?)

Also, when you defeat the weapon that's flying about, it releases Cloud's Ultima Weapon sword. You could argue that the planet allowed Weapon to die in order for Cloud to gain possession of the sword to give him a better chance of defeating Sephiroth.

Well, that's my take on things anyways...

i think this is way over analytical, but anyway:

the weapons were realised, and Shinra etc automatically took them as a threat...symbolic of human natures hatred of things it dont understand (eg: ufo's...we'd try and shoot em down and dissect the aliens)

thats wot i thought anyway.

Weapons may have been against shinra to kill all of the non cetras because they decided to quit the journey. Or they are after shinra because of all the makou which was taken, Then gone after Cloud because he used to work for shinra

If you notice none of the weapons don't go after any member of your party, Diamond Weapon was only after Midgar but you get in the way so you fight it.

So I don't think any of the weapons are evil, there just doing there job.