If i had a two restricted weapon on legolas and i want to play a third restricted to him. Can i discard one restrited to play the new restricted card on him ?

Yes, whenever a character has more than 2 restricted cards, it must discard enough until he got 2 left.

Sorry to break in here, but I too have a restricted item question. So each character is limited to 2 restricted items, can they both be the same restricted item? And can other characters use the same restricted item?

Ok, that was 2 questions...

Yes, as long as they are not Unique , their can be any number of a card in play (you are limited to 3 in your deck, but other player can play them too).

Edit : Nothing to do with your question, mind you, but it's for my parenthesis. I read booored post this in another thread :

Page 9 Core Rules
No more than three copies of any ally, attachment, or
event card, by title, can be included in a player’s deck

Make me remember that I forgot to say it is indeed by title, and not just a card.