how to change the equipped weapon of a city guard ???

Depends, which game, which console, and in-game or in the Construction Set?

I'm guessing you mean in-game. The easiest way, I've found, is to simply kill them, take his weapon, and put a new one on his corpse. If you're playing Oblivion, you could probably make him change on his own by putting a much better weapon on the ground next to him, and make him get in a fight. He might pick it up and use it.

pc. I just want that all city gaurds in oblivion equipped with swords and shields(from their own city) . how do I fix that ? I think not ingame

Could you explain that in more detail please.are you using a MOD editor? are you just trying to convince a gurad to pick up a wep.Details please

Ah, you'll want the Construction Set section of the Oblivion forums. I'll go ahead and tell you here though.

If you don't have the Construction Set (for modding), download it on the main Elder Scrolls site.

Open it up, and check Oblivion.esm as your main file. Once everything's all loaded, look through your object list and find NPCs. I'm not entirely sure where to find Imperial Guards, but once you find them, double-click to open their info up. Go to the Inventory tab and you'll see his items. Select any weapons that aren't what you want, and press the Delete key on your keyboard. Then, in your Objects window, find the weapons and shields you want, and drag them onto the NPC's inventory list. Save your plugin, activate it, and you can play it.

That's the short of it. It might be a tad bit complicated at first, but there are many modding tutorials online, and a whole Construction Set Wiki.

oke thx i hoop this wil help