1-3. damage to inside of the off-hand arm, mitigated some by wearing an arm guard (anyone who's really shot off more than a couple arrows knows about THAT one.)
4-5. string snaps
6. Bow stressed, make a save vs crushing damage at minus something or another or the bow snaps, and the character takes some damage.
But... but... "arrow goes thru both ears of the target cleaning out all ear wax and killing the target dead, dead, dead" is too fun a result. I miss critical hits.