Is it possible to change a certain item's description and name? I mean, the items stays the same, i just want to rename it with my name in front of the name of the item for roleplaying purposes. Same reason for the description change. If possible, how and what would it cost?

That isn't possible. Items only can be edited during their creation, or by direct database access (= Mur powers).
You could probably get it 'edited' in the way of finding some item creator who agrees to make a new item and take the old item as cost for it. Then that'd just require a WP, and of course it'd be a new item that's pretty much the same as the old, so it might be hard to find anybody who agrees to create such duplicates.

Thanks, Burns. I just want to hear an item creator's opinion as well if possible.

It is as Burns said, technically, we don't have any means to change a created item's name. Your best bet would be as already suggested, although I personally don't really prefer to do so unless there is a means of deleting the old item completely from the database. Sure, I can just throw the old one on an alt and let it gather e-dust, but it's still technically there, so there's a double existence paradox, and you don't want to make the world explode! xD

mail council and ask for a change suggesting you would "spend" a wishpoint to change it?

The problem with the subjective item changes is that if the Council approves one, especially if it's posted on the forum like this, then four more might come in, and perhaps one of those four is an item that was only loaned to the one requesting the changes, and so the Council gets flooded with mail about item changes and there's one more reason for us not to trade. But, y'know, it's still worth a shot, as much as anything else is.

I appreciate all the quick answers. The options are quite clear to me now. You may close the topic. Thank you!