Well said.
But I think their mother did this on purpose. Mother already know that the son is very powerful. She know that he already reached the peak and theres no more to improve. But to let him be limited to that territory learning things he already know or things he don’t need to learn is just meaningless. It’s true that he was discovered to be skill-less in front of lots of people, but that just because the one who is doing appraisal was not capable to see his true power. The mother who think that his son would be better off go out, see the vast world, and pursue his dream to learn magic, mother decided to give him the freedom to do so. And so that no one bad will approach his son to try to covet the power, or interested in his affair which could bother him, mother decided to get everyone to treat him as non-existence...
This act maybe a tad bit overly done... his mother truly love him. That if he stay as the heir or stay as a mere child of the house, while it was known he was supposedly skill-less, the son won’t have the opportunity to pursue his dream of learning magic, because he need to stay at the fief at all times to protect the border, doing the documents, managing the land, etc. no time to go out to research magic, not time to meet new people, experience new things which would have helped him to learn the magic.
So this is his mom’s way to protect and to love her son, and give her son the chance to do what he wants.
This manga actually reminds me of the manga where the MC is labeled classless. The difference here is MC is already OP and nobody recognized it at 1st but the mother. He is already a huge threat to both sides and it wouldn't be good if it was known. Mother's decision actually probably saved their family and MC from much trouble. As for the sister, good that she now knows the hypocritical people surrounding her. She now knows who she can truly trust from how they will treat her when they 1st meet her rather than the false pretenses. It may be frustrating and it may hurt both her pride and/or feelings but it is better for her to realize this now then later when it becomes too late. At least she also can acknowledge her brother's strength now too...
Sure, just search classless in search engine of mangago or here...
http://www.mangago.zone/read-manga/mushoku_no_eiyuu_betsu_ni_skill_nanka_iranakattan_daga/
well actually i didn't think that she is stupid or mean or anything like that, i mean... once they still a kid everything about family household should be handed over to her brother and she believe that her brother is worth and admiring him and believe that he will have some great skill or she thought... theennnn she finally found out that her brother is disowned and she must learn what her brother learn since kid to be the head of family
and when she want to see her brother she sees that her brother is still same and do what he want although he already disowned ( like he didn't care about that)
and it's make her mad like.. you know like someone job handed to you and you have to responsible to that job even actually it's not have nothing to do with you it's suffocated (or so i though)
even she get praises it's only make her heart more in the corner, she desperately survriving in her household after her brother kicked out and after she sees that her brother is still the same it's make her more and more in the corner, like ''is it only me that yearning him to be by my side'' her family and ppl surround her keep telling that she should forget about him and make him to be example of failure
and probably bcs of what ppl say about her brother make her confused should she forget and mock him or still became a loving little sister
actually i feel bad of her, i mean in this case i though the one that should be gave an a big slap in their face is their family, her and his family is a trash and even provoking her to hate her brother to some extend ┑( ̄Д  ̄)┍