I finally got around to looking at Odin's script. His attack sequence per turn is:
1. Attack
2. Attack
3. Attack
4. Change graphic
5. Do nothing
6. Use enemy spell "Odin"
7. Attack
8. Attack
9. Change grahic
10. Do nothing
11. Use enemy spell "Odin"
12. Attack
13. Chain: Change graphic, set condition flag to 01
14. Set condition flag to 00 and use enemy spell "Odin"
[repeat from beginning]
His reflex sequence is: if condition flag is 01 and hit by lightning-elemental spell, display message 0x68 ("Thunder struck Odin!") and cast Vanish (instant kill) on self.
So, his script really is funky. You can only hit him with lightning to end the battle on every third time he raises his sword. And, for that one time, there's no pause in between the graphic change and the attack. You have to have pretty good timing (although you should be able to use any lighting spell, even Lit1, which would cast quickly). The weirdness of the script seems like a mistake to me, but perhaps that's how the programmers meant to write it. Anyway, mystery solved.