What is the difference between a Keviyah, a Petza and a Chaburah?
Rashi and Rashbam: "Keviyah" is a burn, "Petza", a wound (that has drawn blood - such as one caused by a sword or a knife - Rashi in Yevamos, 75a) and "Chaburah", a bruise. 1
See Targum Onkelos in Bereishis 41:23, Targum Yonasan in Yirmiyah, 13:23 and Ibn Ezra.
Why does the Torah find it necessary to list these types of wounds independently?
Rashi and Targum Yonasan: Whereas the previous Pasuk was discussing wounds that constitute the victim's devaluation, the current Pasuk is discussing wounds that are confined to pain alone. 1
Ramban: Refer to 21:24:151:2*.
Rashbam: Whereas the previous Pasuk was discussing where the striker destroyed a limb, the current Pasuk is speaking where he did not, and he is Chayav to pay Tza'ar Boshes and Ripuy.
Bava Kama 26b, "Petza Tachas Patza" teaches us that a person is always liable for damages that he himself inflicts - even if he is merely a Shogeg or an Oneis. 2
Bava Kama, 27b: The Torah comes to teach us that one is Chayav to pay for Tza'ar, Ripuy, Sheves and Boshes even where there is Nezek as well.
Bava Kama, 88b: The Torah mentions "Chaburah" to teach us that he is Chayav for "Keviyah" even where there is no wound. 3
Having written "Keviyah Tachas Keviyah" which includes Tza'ar, why does the Torah need to insert "Petza Tachas Patza"?
Rashi: To teach us that, even if the striker has to pay Nezek (damages), this does not absolve him from having to pay for the Tza'ar as well. 1
The case is where Reuven severed Shimon's hand with a sword, and we assess the Tza'ar by how much a person wold be willing to pay to have his hand severed using ointment rather than a sword. See Rashi.
How do Beis-Din assess pain?
Rashi: They assess how much a person with a similar disposition to the victim, would be willing to accept to be pained in this way. 1
