While the connection between witches and hags is often overstated in the common imagination (hags are as likely to patron oath breaking warlocks as have anything to do with the path of true magic), hags are inherently magical beings and there are those among them that walk the path of true witchcraft. Indeed, hags are more likely to do so than any other non-humanoid being, and such hags are more likely than most to teach the secrets of their magic, some of them at least, to mortals who are willing to learn, sometimes even inviting mortal witches into their covens.
At 2nd level you add the affliction schools spells to your list of witch spells. You can also cast the disguise self spell at will.
Also at 3rd level you manifest claws, which you may use to make unarmed strikes. These claws deal 1d4 damage and you can use your spellcasting ability modifier for attack and damage rolls with them.
At 6th level the damage increases to 1d6, at 10th level it increases to 1d8, and at 14 it increases to 1d10.
Lastly, when delivering a touch range spell, you may choose to make a claws attack as part of the same action. If the spell requires an attack roll, it uses the same roll as the claws. If the spell does not require an attack roll, it only takes effect if the claws hit and expends a spell slot even if it misses, but the target has a -d4 penalty on any saving throw against the spell if it hits. They may deliver touch spells in this way a number of times equal to their proficiency bonus and regain all expended uses when they finish a long rest.
At 6th level, you've mastered some of a hag's power of corrupted fey bargains. You gain the other option from A Blessing and a Curse that you did not already choose. Normal uses of the ability are shared between both.
You may also use either one without expending a use of the ability. If you do so to grant Witch's Blessing, then the next time after the affected roll that the affected creature succeeds on a roll of the same type (attack, check, or save), they are automatically affected by Witch's Curse. If you use it to impose a Witch's Curse, the next time after the affected roll that the affected creature fails a roll of the same type, they are automatically affected by a Witch's Blessing. Once you have used this ability on a particular creature for free, you cannot do so again on that creature until you finish a long rest.
At 10th level you gain the Coven Casting ritual mastery option, or a different ritual mastery option if you already have it. Furthermore, by linking with two other creatures using this ability over a short rest each of the three creatures can regain a spell slot of 5th level or lower. Furthermore, any one of the linked creatures can expend a spell slot in order to allow a different linked creature to regain a spell slot of the same or lower level. Once you have used this benefit you cannot do so again until you finish a long rest. You must have exactly two allies with ritual casting that you can bond with for the full duration of the short rest to use this ability.
At 14th level you learn the enduring bestow curse rare spell if you do not already know it. You always have bestow curse and bane prepared, they do not count against your number of witch spells prepared, and you may cast each of them at their lowest spell level once per long rest without expending a spell slot