Here's what happened, your opponent won the match, but when he inflicted the final blow he died because of your reflect damage. Since he was the one who inflicted the final blow that makes him the winner of the match, and for some reason you get karma ( which is the match supposed to be a tie )
all tribes has its reflect skill some on passive skills like satya some on buff like in the banar and some on the items... you killed your opponent by reflected damage... i mean when you badra him/her then simultaneously he also achibata you therefore he/she survived your badra but his hp was very low and therefore when the achibata was casted and damaged you, your hp is not enough to tank his achibata you were killed but then remember he only had little MP so when he damaged you with his critical skill some of that damage returned backto him because of your reflect skill...
here is my video way back my amped days, anagami server watch how my opponent killed me when i won the duel... watch 1:19 and 2:08 minutes... enjoy watching...
hope this video answer your question.