5.33 From the first time I read 5.33 I didn't understand it as a legal punishment, but rather as what I think is called poetic justice. If it was a legal punishment, as has already been explained it would not have that formulation, I do not think that the word jazaa'u can legitimately be taken as meaning legal punishment. In pedagogic litterature like for children where they are taught that bad actions lead to unhappiness, the word reward might be used, also in plainer speech, it could be used and in fact very likely used sarcastically when one behaves usually in a nasty way and somewhere along the line gets slapped with something nasty, tastes his or her own medicine. Those who live among criminals get definitely to taste at some time what criminal can do to others, who may be also criminals. That would be the reward for their being so "clever" and "above" good, simpler minded people. The point is that in that aya and in the contest I do not see anywhere any punishment except those inbedded in nature laws, which are also God's laws. As to those who repent, that is also plain, if they do not join the criminal crowd, they are not exposed to the rewards. Obviously after they are in believers hands there is no reason for them to fear anything. If they repent afterwards, they would fall under the general category of repenters and the general rules for repentance would apply to the them, whatever they are. Also, it may be understood that when they repented when still banding with the corruptors they earned God's forgiveness and protections.
In 5.38 it is equally the term jazaa' that is used, which for me means not a punishement, but in view of imperative mood, it would be a "reward" to be applied by those addressed, that is, those who believe, and the reward would be to "cut the hands".
I would point out that the verb used in 4.33 and 5.38 is not the same. In 5.33 it is form II, it is form I in 5.38.
Given the use of the term yad (hand) in Arabic as a synonim of capacity or power and the use of hands (in the plural, and not in the singular or dual) I take it that yad is meant precisely in the sense of capacity or posibiity.
Salaam