Third person Sword Slashing may be popular, but there are many different techniques for implementing the mechanics. Making the decision on which one to use or creating something different is where challenge is.
For example, I considered melee combat for my FTPS. My technique was to reuse the Firearm Weapon projectile/fx/damage systems. The concept was to fire tiny projectiles from the handle’s axis pointing up, during the swing. I believe i can do something interesting with collision detection and damage effects. For more dynamic animation, i was planning a IK system vs pre-recorded animations.
No matter what techniques you pick, It will be beneficial to get familiar with UE4’s Skeletal Mesh Animation Systems to create blendspaces/montages, statemachines, and notifies… to wire up animation to events.
For Dodge and Rolls, you could use a animation set like this…
You can find it here