[phiwum]

You did do avoid with the do-over roll, Steve, but you changed the odds. By subtracting one from the roll, the odds are:

3/6 - Initiate, no dagger drawn
2/6 - Initiate, dagger drawn
1/6 - No initiation

The odds in RAW are

2/5 - Initiate, no dagger drawn
2/5 - Initiate, dagger drawn
1/5 - No initiation

Whether that's an improvement or not is up to you, of course. There's certainly some sense in lowering the odds of drawing a dagger or pushback when attacked from the rear.