DELIMITER //
CREATE TRIGGER `fight_update` AFTER UPDATE ON `fighter`
FOR EACH ROW BEGIN
UPDATE `fight` SET `F1_Name`=NEW.`Name`, SET `F1_Name_eng`=NEW.`Name_eng`, SET `F1_Nat`=NEW.`Nationality` WHERE `F1_ID`=NEW.`ID`;
UPDATE `fight` SET `F2_Name`=NEW.`Name`, SET `F2_Name_eng`=NEW.`Name_eng`, SET `F2_Nat`=NEW.`Nationality` WHERE `F2_ID`=NEW.`ID`;
END //

Пишет:
#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'SET `F1_Name_eng`=NEW.`Name_eng`, SET `F1_Nat`=NEW.`Nationality` WHERE `F1_ID`=N' at line 3

Спасибо, понял.
И еще после END нужно вместо // поставить ;