Path of the North

You are an explorer, who longs to discover places that no one has ever seen before.  You are a sailor, using your senses and the stars overhead to guide your boat across the sea, at home on the waves as much as you are on land.  You are an invader, who longs to walk among your enemy and relieve them of their belongings and families.  You are a berserker, overcome with maddening rage, tasting the blood of your enemy as you attack again and again, as you drive the blade of your war axe into their bodies.

Winter's Fury

When you are under the influences of your rage, your attacks begin to take on the cold fury of your home.  Beginning at 3rd level, whenever you are raging and using a battleaxe or greataxe, your first successful hit each round additionally does 1d4 cold damage.  This cold damage increases to 2d4 at level 6, 3d4 at level 10, and 4d4 at level 14.

Fjord Mists

Beginning at 6th level, your vision is completely unimpaired by cloud, fog, and mist, even if magically created, out to a distance of 20 feet.

At 6th level, when you enter a rage or as a bonus action while raging, you can create a 20-foot-radius square of mist centered on you.  This mist area is heavily obscured, causing all others within the mists, or those attacking with ranged attacks into the mist, to attack at disadvantage.  The mist lasts for 1 minute or until a wind of moderate or greater speed (at least 10 miles per hour) disperses it.  When you move on the battlefield, the mist will move with you.  Once you use this feature, you can’t use it again until you finish a short or long rest.

War Cry

Beginning at 10th level, your war cry has become more powerful.  While raging, as a bonus action you can let out a war cry for all to hear.  At the sound of your fierce roar, all enemies who can hear you must make a Charisma Saving throw (DC is 4+ your barbarian level), or else become frightened until the end of your next turn.  At the sound of your war cry, all of your allies gain an advantage on their next attack roll.  You can only use this ability once per short rest.

Bloodthirsty

Beginning at 14th level, whenever you kill a foe while raging,  you can tear a limb or head, or another easily accessible body part, from your foe and hold the trophy in the air overhead.  All living foes who are in sight of you must make a Wisdom saving throw (DC is your barbarian level), or they will become frightened for a period of rounds equal to your charisma modifier (minimum of 1).

Sailor

You are double proficient in operating sea-going vessels.  You know the many tasks needed to sail a ship on the ocean.  Beginning at 1st level, you are capable of sailing on any sea-going ship.  With a crew of six, you can easily pilot a smaller ship or long boat, even if they aren't as proficient as you are.  When in a battle on the seas, you gain the ability to use the roll of the sea to gain an advantage to your first attack each round, while at the same time causing your enemy, if they are not sailors, to attack you at a disadvantage.

The War Axe

Beginning with 1st level, you are very proficient with a battleaxe or the larger greataxe.  These are the weapons of choice among the warriors of your clan, and  you wouldn't be caught dead without yours.  It is more important to you than anything else you own, and you feel naked without it.