your unfortunate curse is quickly becoming your greatest tool. with this power or rather anti power you have gained the ability and absorb the magic of those around you and negate or reflect any spells coming back at you. 

Bonded Blade

At 3rd level you learn a ritual that creates a bond between yourself and one weapon. You perform the ritual over the course of 1 hour, which can be done during a short rest. The weapon must be within your reach throughout the ritual, at the conclusion of which you touch the weapon and forge the bond.

Once you have bonded a weapon to yourself, you can’t be disarmed of that weapon unless you are incapacitated. If it is on the same plane of existence, you can summon that weapon as a bonus action on your turn, causing it to teleport instantly to your hand.

You can only have one bonded weapon at a time and if you try to bond with a second it will remove the bond from the first.

Anti-magic Runes

At 3th level bound weapon gains a number of runes that will recharge at the end of a short rest the amount of runes is equal to barbarian level. These runes can be used in a multitude of ways. These mysterious glowing runes running the length of your weapon feed off of the anti-magic in your body and will recharge themselves after a short rest.

Deflection your instincts have been honed to predict and deflect oncoming spells. While wielding your bonded weapon you can deflect any magic coming toward you. can use a reaction when a magical effect (spell, dragons breath, beholders eye rays etc.)  that includes you with its area of effect that would deal damage to you. you can reduce the damage by 2d6 + your strength modifier + your proficiency bonus if you manage to reduce the damage dealt to you to 0 you can use one of your runes to deflect the spell back at the caster using them as the new target. 

The dice of the amount of dice of this ability goes up to 4d6 at level 5 and 6d6 at level 11 and 8d6 at level 17.

Anti-magic

At 6th level your have begun to grow accustomed to the strange new runes and have found a few more interesting ways in which to use them.

Anti-magic slash You can expend one of the runes to make a weapon attack on a spell creating the effect of the dispel magic. the attack will be rolled as a normal weapon attack using your bounded blade against your targets spell save dc on a successful hit you push through the targets magic and manage to severe the arcane bonds feeding the spell. 

Mind Shield You have learned that the runes have also provided some more defenses against effects that alter your mind. If a creature forces you to make a saving throw against being charmed, frightened, stunned, or paralyzed your bonded weapon will help bolster mental defenses. as a reaction you can absorb one of your runes to grant you self advantage on a saving throw against these effects. 

Magical Absorption

At 10th level your body has begun to grow accustomed to the backlash of the spells you have been defending against.

Strength of Body While raging you gain resistance to acid, cold, fire, lightning, and thunder. If damage by one these elemental damage types you can store its energy in one your runes. The next attack made with your bonded weapon you can release the power stored in the rune dealing damage exactly equal to the number you took after resistances where calculated the type matches the element you where originally hit with to charge this rune. The damage dealt back to the attacker cuts through any resistance they may have to the elemental damage type stored in the rune.

Kindred pain Having taken the brunt of as many spells and attacks as you have you've learned how to use some of these cheap tricks to your advantage. using one of the runes on your bonded blade you can gain a temporary boost of adrenaline allowing you to hit your much harder than normal. The target hit with this adrenaline surged attack must make a constitution saving throw(DC= 8+proficency bonus + strength modifier) or be stunned until the end of your next turn.

Anti-magic overflow

at 14th level upon entering a rage you can let your body sprout black wings of negative magic energy that grant the following benefits, you gain a flying speed equal to double your walking speed.  at the beginning of your turn your regain hit points equal to twice your constitution modifier, and you may add you strength modifier as necrotic damage to any weapon attacks you make with your bound blade you can only use this ability twice per long rest and after the second time you gain two points of exhaustion.