Here's how I look at it:
When considering if something is hazing...think, "would I do this to a friend or family member to make them closer to me?" It's a good way to think about it.
Anytime pledges/new members are degraded, made to do extra things that don't serve a good purpose, etc, it's hazing to me.
If it makes pledges/new members nervous, afraid, annoyed, etc etc then it's hazing.
Pledging should be a positive thing. It shouldn't be something you struggle through to "earn your letters."
Although I *personally* do not think it is hazing to not allow pledges to wear letters until initiation. Then again, this is a national policy for us so it's okay for other orgs to have differing opinions.