I have an untrained pet and I need to know what weapons I should use to help him battle.
have a look here for a full weapons list by tier. Untrained pet = Tier 1.
The Shinwa weapons are pretty good for that tier, but there are really no "best weapons" - you need to pick weapons to suit whatever opponent you're fighting, things that defend against the specific kind of damage they do. The Useful Battle Threads sticky is another place you should look.
Personally, if I were just looking for a good, cheap set for a Tier 1 pet, I'd get the following:

^ Echo wrote the guides and knows better than I do XD
I see, I'll go get the following weapons then. Thanks for your help! :D
Pft, I'm by no means an expert. There's a big difference between copying info down and actually knowing what one's talking about, and half the time even I don't know what I'm babbling on about. But this is generally the set I use when trying out the plot baddies that can be beaten by untrained pets, so I'm pretty comfortable with this one. Shinwa's weapons work great as well, Tier 1 is pretty unique in the fact that there's no one best set. There's a lot of good choices, and it's hard to go wrong. Unless, you know, you fill your set with only sporks or something. You'd have to be Insane to do that. :P
I suppose I should explain my choices a little. The Staff of Lore will be the main weapon in your set. It's actually the best healer for Tier 1, ignoring the expensive scaling weapons. The Love Wand doesn't do a lot of damage, but it's nice if you're trying to turtle your way through an opponent and need a bit more healing. The Krad Bomb is obviously a bomb, you can use it when you're trying to do more damage then normal, And the Pumpkin Wand is one of the highest damage dealers for Tier 1. Thrashing Bulldog does very good damage for Tier 1, and is one of the very few Tier 1 weapons that has a mod slot. The Quill is good for a one-shot heal during a battle. Most of the time, I use the Staff of Lore and the Thrashing Bulldog.

So the Staff can both heal and damage? :D Are all those weapons reusable?
Yup. The staff actually does damages, defends a few ice icons, and heals your pet 10hp each turn. If you look them up either on the Weapons guide or on Tier 1's pet page, (Both linked on my profile), it'll show what they do. Unless specified, most weapons are infinite use, meaning you can use them as much as you want. The bomb and quill are known as Once Per Battle (OPB). That means you can only use it once in that battle, but as soon as the battle's done, you'll have it back in your set again.
If you want to know more about how battling works on here, check out this guide as well.
