i was wondering if you could give me a hand

This is my first cosplay i and am wanting to do Zabuza (from naruto) and i am wondering what should i make the sword from and where would i get the materails for his trousers

Reference pictures?

Try balsawood for the sword. Trousers you can buy in the right colour and with a steady hand and a ruler draw lines down them with a sharpie to get that pin stripe effect. You can get pin stripe fabric but those stripes are very wide and no guarantee a fabric exists replicating that. If you want to make your own trousers from scratch, buy a sewing pattern from a shop and use that

As Mycroftwave has said reference pictures would help and may increase your chances of getting answers.

Balsas really good to work with but not very sturdy. That's what I used to make my buster sword.

You could also use a technique similar to this for the sword, I know it's a katana but the same technique could be used for a larger weapon as well. You can get plastazote here but you could also try using craft foam which you can get from there as well. If you're looking for a cheaper foam you could get yoga/camping mats and trying that as well.

An alternative I have found quite good is simply using polystyrene sheets you can pick up in Hobbycraft. They can be cut to shape and after they're been fibreglassed or papier mache'd then they're not as flimsy as you would think, especially if you can fit them around some dowling.