Final Fantasy III

I started a new game today, and had a very strange experience fighting the griffin in the left tower of sassoon castle. I got about half way through the tower before most of my party was killed, leaving only my back row black wizard. For kicks I decided to grab the w.slayer and suicide against the griffin.

I managed to sleep him on the first round, and then attempted to run twice. He woke up, missed me once and resisted sleep. He then hit the black wizard for most of his health. On the next turn I had my black wizard do a melee attack with his two daggers, and to my suprise it did upwards of 2000 damage, killing the griffin instantly.

I double checked his stats post fight and they all seemed to be pretty normal. This is probably my sixth or seventh time playing through ff3 on the nes and I've never seen a damage calculation go so haywire like that- I cannot fathom how a level 6 blm would do 2000 damage on anything with a pair of daggers. I tried to have him attack other stuff but he was back to hitting for 8 to 10 again.

Is this documented anywhere? Sleep is a very underutilized spell so I wonder if there's an undiscovered glitch with it.