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) and "Chaburah", a bruise. 1
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
Rashbam: Whereas the previous Pasuk was discussing where the striker destroyed a limb, the current Pasuk is speaking where he did not.
Such as where he burned him with a boiling spit-rod on his nails. The Gemara in Bava Kama 26b, also learns from "Petza Tachas Patza" that a person is always liable for damages that he himself inflicts - even if he is merely a Shogeg or an Oneis. See also Torah Temimah (Note 176).
Rashi writes that "Petza" refers to a wound that draws blood. It can obligate the striker to pay Sheves, Boshes, Ripuy and Tza'ar. Why does the Torah see fit to write "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
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