I've been thinking about this parable. For context, "adultery" is better understood as the bride (Israel) being unfaithful to God (Eze 16.35-36) in all forms (e.g. idolatry).
Here are some readings:
1. First reading: weakening to allow redemption
"If your right hand causes you to sin". The right hand is a symbol of power and strength (Ex 15.12,6; Ps 98.1; Ps 20.6; Ps 118.16). Hand (yad) means power, hand, monument, etc.
So your "right hand" can cause you to commit adultery if your own power causes you to be arrogant and rely on your own strength. Then it is better to weaken yourself (cut off your right hand) and make yourself powerless than to be unfaithful to God.
"Right eye" - eyes are how we perceive the world, and the right side was viewed as the side of wisdom (Ecc. 10.2), so the right eye could be a reference to what we perceive to be wise. Thus if what you perceive to be wise is causing you to be unfaithful to God then it's better if you destroy that and don't consider anything wise than to be led astray (1 Cor 1.27-29). 2 Cor 12.10
2. Second reading: weakening as becoming childlike
In Matt 18, Jesus speaks to his disciples the same themes, so we can learn the parable more openly. This time it is the hand (again, power/ability), foot (halach, or our walk/manner of life) and eye (how we judge the world).
in v3-4, we should be like little children. Little children are weak, they are dependent on others to lead them, and they are innocent, making few judgements (some say naive). Unless we humble ourselves and become like this, we cannot enter the kingdom.
v4-7, whoever takes care of the little ones takes care of Jesus, and whoever leads one of them astray, it would be better if a stone were attached to his neck and he were cast into the sea. (c.f. Eze 28.8, Zech 12.3)
v8-9 The limbs come off. Better to enter life crippled than the whole body burn in hell. Here we have the idea that even in Heaven we are crippled. This is new. We are reminded of the blood Moses put on the high priest (a drop of blood on the right hand, right foot, and right ear, Ex 29.20). So now in Heaven, we will not have our own power (hand), we will not do our own walk (foot), and we will not judge for ourselves (eye). We will be in complete submission to the Father. Now the maiming takes on a mandatory nature, rather than "if..".
v10-14 parable of the lost sheep. But also the parable of the good shepherd. God wants to bring back those who wander off.
So summarizing Matt 18, we have that we need to be as weak/dependent/innocent as children if we are to enter heaven. But children can easily be led astray. Woe to him that causes them to stumble, even though it needs to happen. So now the children are led astray and we switch to adults. Adults need that weakening to enter heaven in that dependent, childlike state. Those who don't will have their whole body destroyed in hell. God will rejoice over bringing back the lost to his fold.
3. Third reading: Redemption via the cross.
Read Zecharaiah 11.16-12.14, where there is a similar story, except God becomes the actor triumphing over evil, and the role of the bride is passive. That's good, as self-circumcision is hard.
v 16: There is the bad shepherd that doesn't care about his flock and sells them to those who would destroy them. So the flock is being led astray. God has calamity strike the foolish shepherd:
v 17 “Woe, my worthless shepherd who deserts the flock! May a sword fall on his arm and on his right eye! May his arm wither completely and his right eye be utterly blinded!”
We then have a type of spiritual war, in which God is protecting Judah, making it immovable, and striking her enemies with blindess (v4) and "I will strike every horse (metaphor for strength) with confusion".
The spiritual war continues, and God declares Judah will no longer be able to stumble (v8)
v10 "“ ‘I will pour on the house of David and on the inhabitants of Jerusalem a spirit of grace and supplication, and they will look to me whom they pierced, and they shall mourn over him, as one wails over an only child, and they will grieve bitterly over him as one grieves bitterly over a firstborn."
Grace and supplication is that dependent, childlike state which allows Judah to see Messiah and then have each wife mourn alone in repentence.
To summarize the third reading, it is God who will destroy the strength/walk/judgement, and this is the prelude to the bride no longer being moved by her (spiritual) enemies - she becomes very heavy (heaviness = glory), like a stone they can't move, like a stone that crushes them. She adopts the childlike attitude that allows her to see the cross, and then bear that cross alone.