You can get new items from crates and in quests as well.

Keep in mind that as you progress on the World map, you will also be able to obtain items as rewards. You'll even be able to receive new items by winning various battles, since you'll even be able to collect some in-game coins to exchange for rewards of various levels.

In addition, there is always the option of making your own items, either in the supply workshop or the weapons workshop.