This tutorial series covers how to add a knifing/melee system to the Multiplayer Zombie Survival Template. Animations, sounds, and sword assets are from Epic's Sample RPG project. They provide that free product as a learning tool for developer to use and learn with.
Buy it now on the Unreal Engine 4 Marketplace: https://www.unrealengine.com/marketplace/en-US/product/multiplayer-zombie-survival-template