i need help, i am at helms deep. i have helped gimli and legolas. and i can survive helping aragon, then defeat the troll, then the last bit is with a troll, and 3 urak-hai. i am on easy, and i cant survive the last one. i have a perfect and use but it doesnt kill them all because, another comes and more unak-hai comes. but the elf doest have the valour how do i defeat the last bit and how do i get the valour pls someone help

yeah, if you dont have Aura of the Valour yet, dont start the battle. instead travel back to elgion and learn AotV. i dont know if you have it yet and if your past Helms deep, but if not, or for anyone who isnt, here's step by step how to get AotV (or a good way to get whatever power you want):

1. When in Elgion, go to a save point then run around till enemies attack you (preferrably, you want at least one of those orcs with the flag that can only do magic attacks.)
2. Now, first kill off all the other guys not including the flag dude.
3. Now, have everyone except Idrial retreat.
4. Now cast Drain Inspiration a couple times on the flag dude so that he cant do anything but stand there like an idiot. If you dont have Drain Inspiration, you are going to need to learn that first unless you dont mind the flag guy pummeling you with those annoying crows all the time.
5. Ok now Idrial will have unlimited turns. So pick a spell that takes a short ammount of time and costs a low AP. I like Gift of Elrond. Takes 4 seconds to cast and only costs like 15 or 20 AP. Continually cast that on herself until you learn Aura of the Valour. But it will take a while so be patient. After you learn it, set your spirit power learn skill to Power of the Valour. This is similar but revives a character that has already died. You dont have to learn it right away but every time you either heal someone or do AotV, Idrial will get points toward it.
6. Now that you have AotV, when you fight those Uruk in Helms Deep, cast AotV on the whole party starting with Idrial and you should be good to go.

NOTE: replace Aura of the Valour with whatever other ability and character you want to learn.

thats where i could'nt do it as well but i did after 4 treis

It's best if you focus on getting spells like this while your inside Moria -- the amount of goblins and such, among with the constant levelings, gave me a huge pool of health and such to work with, and skipping over a few spells to get it is worth it.