I can only see 1-2 en garde at blacksmith, how can i get +3 i can see at maxroll character planner? And waht if i get just +1 rank, can i retemper indefinitely?

Keep re-tempering it and you can get a Greater Affix temper. At the top, you'll see the button to use the scrolls you've been looting. It will restore a charge of tempering, and you can keep trying over and over. Depending on the item, you may want to be a little conservative with it.

However, that is how you can get your +3.