Review my Magic Item: Ring of the Helping Hand

RING OF THE HELPING HAND

A silver ring, tarnished by years of neglect. 

While wearing the ring, you gain the following benefits:

Helping Hand. As a bonus action, you may snap your fingers with the hand that wears the ring. This causes your hand to painfully but harmlessly sever at the wrist. Your hand gains the statistics of a Crawling Claw, except that it adds your proficiency bonus to its Armor Class, Hit Point maximum, and attack bonus. The helping hand acts immediately after you in initiative, and follows your mental commands as long as it is within 60 ft. of you. While your hand is severed, you have disadvantage on attack rolls and ability checks that would be hindered by your missing appendage. 

Reconnecting. While the hand is within reach, you may spend a bonus action to re-attach it, good as new. If the hand is reduced to 0 hit points or ends its turn more than 60 ft. away from you, it is magically re-attached, dealing 2d8 force damage to you.

Once you use the ring in this way, you may not do so again until the next dawn.

A few suggestions:

• Adding your proficiency bonus to the hand's HP is unlikely to ever make any difference in practice, since one hit from almost anything will still take it out even with those extra HP. If you want it to be able to take a hit in combat and survive, maybe make the extra HP something like 5 times the owner's level.
• People are likely to want to use this for scouting purposes. Consider stating explicitly in the description whether or not it's capable of telepathically communicating back to the owner, and whether or not the owner can perceive through its senses. (Either way is probably fine, but it's going to be the first thing a lot of people ask about it, so it's good to spell it out.)
• The part about disadvantage on certain ability checks is fine, though it's on the DM to adjudicate when it's appropriate. But I'm not sure extending that to attack rolls makes sense. Weapon attacks are generally made one-handed (which should be possible to do without penalty when you only have one hand) or two-handed (which shouldn't be possible to do at all with only one hand). In neither case does it really seem to make sense to be able make the attack roll with a penalty.