Uhm i noticed that if you play an evil type of character you get easier better weapons is a good knight useless?

Your characters can change their alignment during the game. If you constantly attack monsters when encountering them you will slowly shift your alignment towards evil, but if you offer bribes instead you'll shift towards good. There are certain items that only work for good, evil or neutral characters. I don't think there is a distinct advantage to one alignment over another.

You can restore your alignment at a temple, or with the restore alignment spell. If you get your good knight to be evil, then give him an evil-aligned weapon, then restore his alignment, he can keep using the weapon as long as you don't un-equip it.

well i noticed that most + 1 weapons you need to be evil alignment.

Possibly, but you will soon be finding weapons with higher "+" values, like +2 and +3. You can check the cluebook for a full list of items and their alignment requirements. It's available as bonus materials from GOG. You can download it by visiting your GOG account page, clicking on the M&M pack, and looking under "additional content". Of course, the cluebook contains spoilers, so be careful. I tried to only use it for item stats.

thanks yeah i foind an hand axe + 1 and spear and a gleave but you need to be evil to use them wich i notice am almost my party is either neutral or evil while they were good when i started.