When fighting other melee opponents be sure to use VATs since those attacks are unblockable and be sure to block often. Aim for enemy limbs or their head when slicing away so as to hamper their ability to fight back. Since VATs only allows you to target the enemy in general you’ll need to do things manually.
You’re going to need to use strong weapons, target enemies vital points and then slice away at them. Playing this character can be somewhat difficult if you’re not good at the game. The hard part to a melee character is that you must wear light armor if you wish to close in on enemies fast enough that their guns won’t tear you to shreds but when forced into a heads up battle against multiple foes with guns light armor won’t help you too much. Many of the enemies are stronger and more dangerous in melee than you are, so it’s a risk every time you get near them also, Deathclaws. A melee character is definitely a heck of a challenge in the Fallout games.