Base Class: Barbarian
Let's be honest. At the time of writing this (April 11, 2021), the Path of the Berserker currently sucks. Easily one of the worst subclasses in the game. Its 3rd level ability literally punishes you for using it, and its 10th level ability is basically useless as it uses an ability score (Charisma) that is generally ignored by most barbarians. In this revision, I seek to give alternative options for berserkers to use at the table should their DM allow such homebrew. This revision may have changed every berserker ability, but they are optional. You can take some of these options, all of these options, or none of these options. Talk to your DM, do what you both think is best.
Mania
Starting when you choose this path at 3rd level, you can choose to go into a manic rage. If you do so, for the duration of your rage you can make a single extra melee weapon attack whenever you take the attack action on each of your turns, including the turn that you went into a manic rage. In addition, you can take the dash action as a bonus action while manic raging. When your manic rage ends, your movement speed is halved for 1d4 hours.
Seething Mind
Beginning at 6th level, you now have immunity to the frightened condition. If a large or smaller creature tries to frighten you, they must then make a Wisdom saving throw (DC equal to 8 + your proficiency bonus + your Strength modifier). On a failure, that creature is then frightened of you until the end of your next turn. On a success, nothing happens.
Frightful Presence
Beginning at 10th level, you can use your action to frighten others with your menacing presence. When you do so, choose up to three creatures that you can see within 30 feet of you. If the creatures can see and hear you, they must succeed on a Wisdom saving throw (DC equal to 8 + your proficiency bonus + your Strength modifier) or be frightened of you until the end of your next turn. On subsequent turns, you can use your action to extend the duration of this effect on the frightened creatures until the end of your next turn. Using and maintaining Frightful Presence extends the duration of rage if rage is in effect. The frightened effect ends on a creature if it ends its turn out of line of sight or more than 60 feet away from you.
Once you use this feature, you cannot do so again until you finish a long rest.
Retribution
Starting at 14th level, whenever a creature within 5 feet of you makes a weapon attack on their turn against any other creature than you, you can immediately make a single melee attack against that creature using your reaction. On a hit, that creature then has disadvantage on their saving throws and ability checks until the start of your next turn.
Exasperated Rage
Starting when you choose this path at 3rd level, the slings and arrows of your enemies can fuel your fury. Whenever you take damage while you are raging, your next attack deals an extra die of the weapon's damage.