Here is how to dismember people in JK3, just like in JK2. This involves editing a game files ! But it works.

1: Go into the Game folder.
2: Find the GameData folder.
3: Find the base folder.
4: Find jaconfig.cfg
(if it is not there, make sure that the window is set to show ALL FILES)
5: Find g_saberMoreRealistic "0" and change it to g_saberMoreRealistic "99"
6: Find cg_saber EntMarks "1" and change it to cg_saberEntMarks "99"
7: Find g_dismemberment "0" or "1" and change it to g_dismemberment "99"
8: Save it.