Question regarding feather damage

[intrepidity]

So, on the bald eagle nest cam I watch (Decorah), for the past several days there's been this male Red Winged Blackbird that has been getting increasingly bold in his aggressive behavior towards the fledgling DH2 (~4mo).

At first it was just kinda funny because for the most part. DH2 ignores him, and the size difference makes it sort of comical. It was mostly dive-bombing pecking attacks, but starting yesterday, Mr. RWBB has been landing on DH2's back and repeatedly pecking their feathers, and no doubt causing damage to the feathers. So I was wondering how serious this type of damage is? I know that whenever I found a feather as a kid, once you separate the strands, they never go back to how they were. This no doubt will have an effect on flight, right? DH2 is too young to know what to do, and the parents don't seem interested in getting involved (although, tbh, I would not be surprised if mom delivers that pest to the nest as a meal someday soon!)

Thoughts? You can scroll back to several incidences in today's stream. Ask if you need me to find timestamps. Thanks in advance.

[Bayard]

1. Isn't he about ready to leave home?

Per Google:

"Perhaps no bird has a reputation for being a bully as much as the red-winged blackbird, and deservedly so."

I'm guessing if you're seeing this behavior, the people running the study are too.

[intrepidity]

2. DH2 fledged a couple weeks ago, but still returns to the nest

frequently, mostly as a food delivery location. It will be many more months before DH2 actually leaves the area.

[Donkees]

3. ''The vane of the feather is formed of many individual feather barbs ... ''

The vane of the feather is formed of many individual feather barbs. Adjacent barbs are hooked together with a series of microscopic hooks, like velcro. The hooks can be unzipped by pulling gently on the barbs and zipped up again by running the barbs through your fingers. Birds zip their feathers back up by preening -- running the bill over their feathers.

https://whozoo.org/ZooPax/ZPFeather.htm

Everything You Need To Know About Feathers
https://academy.allaboutbirds.org/feathers-article/