I've gotta say he looks like a sweetie. My most recent eclectus has taken quite some time to warm up to me, probably months! Lots of growls and nips later and I finally have his trust. He too was a plucker and couldn't fly, so he felt very vulnerable and this would make him lash out. Now we have an understanding and he's a sweetheart
The fact that this little guy has been this trusting with you straight away is a great sign!
Eclectus come across as rather placid. They typically don't run around as much as some other species and like to watch and learn. I do love the crazy energy of cockatoos and such, but the more I watch them, the more I wonder if I could tolerate them being at high energy levels every day! Eclectus are definitely my pace. I was put off keeping small birds as they are so skittish. Eclectus are much more thoughtful and deliberate in whether they do, which for me personally means I can read them better.
Was the noise he made definitely a growl, or was it more like a clicking crunching squelching sound? If it was more like the latter it's a good thing, it means he's relaxed and sleepy, which means he trusts you as a safe place to rest! If it was a growl, it just means he was trying to tell you he either didn't like something you were / weren't doing.
Definitely try to keep him on the hand or wrist with your arm straight down and bent at the elbow as suggested. If he starts to show interest in climbing your arm you can have treats ready in your other hand ready to distract him. If he only receives treats while on your hands / wrists it will build a positive association of "when I sit here sometimes she feeds me goodies". Maybe something like almond slivers? They're small and can be broken into even smaller pieces to make them last a bit longer as too many nuts aren't good for eclectus.
With regards to the piercing, he probably would be curious of it and try to grab it. I have multiple facial piercings and multiple birds and haven't had one ripped out yet

The key is having an alternative thing to occupy them, keep them distracted or to offer them that is acceptable to play with. I'm pretty sure that if my guys were close to my face with no toy or no food it wouldn't take long for them to start grabbing at the shiney
Dexter used to be obsessed with my glasses. If he grabbed them, he was told no and put on a perch or in his cage for 30 seconds and ignored (no eye contact, no verbal communication). Then I'd go back to him like nothing had happened and give him something else to play with instead. If you leave the bird for too long after the negative event they don't make the association between their negative action and your disappearance. Consistency is key when it comes to the training and setting boundaries.
I hope you keep visiting this little guy
