I think we should share our insights - I mean, this is just a bit of basic above board research and it's nice to develop bonds of camadrie and mutual support with people. Would have been better if they were more involved with it but... eh.
Some things should be kept secret for various reasons. Tom's history is not one of those imo.
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Eventually, a weak Alchemy shield-item that can give a boost to the first defence roll of combat might be worthwhile, and possibly also something that can summon one's wand back to themselves. I expect[1] that most adult wizard fighters just learn do it wandlessly, but that's far off for Jacob (though if we do make these items, I'm not inclined to use them during dueling practice).
[1] Well, this is my personal worldbuilding. The original author never explored this idea in the text.
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Edit: I think if there is a concern that this will put the other two at risk, we just have to make it clear that a very evil person has went to at least moderate effort to keep this quiet, so like, they should keep this under their hats.
Dropping the investigation and not saying why, when the other two are involved looks sus, so they are likely to figure it out on their own eventually, so that's just duplicated effort and a potential cause of aggravation/resentment imo