Luke’s been written by so many authors with different ideas that I could write nearly anything in this section. This is my interpretation.
He is, by now, a very forgiving, compassionate man. Gentle, nurturing when he can be. He’s also very, very, very good at combat. And he enjoys it, which concerns him to the point where he’s consciously worked to make himself nonviolent.
In many ways, he takes after his mother. There’s a deceptive softness to him. He believes in the worthiness of self-sacrifice, puts others before himself, and disregards personal desires for what is right. Luke also believes there’s good in nearly everyone. You might say he’s pretty feminine in those regards. He wouldn’t be offended, though he wouldn’t really agree. Kindness and compassion shouldn’t be gendered.
Once he was more impulsive, impatient, and easier to rile up. Now, not so much. His temper is controlled. Feeling even irritation surprises him a little, and makes him evaluate the reason for this feeling. He’s very aware of his emotional state and keeps it carefully regulated. Not getting angry has gotten easier over time.
Few things can rouse that well-buried temper. The big one is threats to other people, particularly people he cares about. Even this isn’t the wild savagery he showed on the second Death Star, but it does display a side that isn’t so nice.
Luke will break himself to save people. When his father Anakin was young and heroic, he sometimes proudly expressed the thought that saving people was what he did best. That doesn’t occur to Luke. It’s something he just does. Cost to himself or how he’ll look doesn’t cross his mind. He’ll put his life on the line for nearly anyone.
He’ll also verbally defend nearly anyone, if they haven’t just been attacking. Complain that a shopkeeper was slow, and he’ll point out that they could have been having a bad day.
And he will forgive almost anything, if the offender is sincere. Attempts on his life? Shirked responsibilities? Murder? Genocide? Yes. Luke can sense sincerity. He does eventually recognize if someone is beyond redemption, and he knows that someone who he’s forgiven still has to answer for their deeds; when he forgives someone he doesn’t simply resolve someone of all guilt, but he does try to help them. He’s actually somewhat less forgiving and more wary than he used to be, but there’s still a lot there. He tends to be softhanded about discipline.
Luke’s sense of humor usually runs towards mildness, but there’s a slight maliciousness to it. If he is meditating and someone comes to gawk - which they sometimes do; Luke will sometimes meditate in weird ways - he may telekinetically cause them to rise.
In a crisis, he’s almost preternaturally calm. Not just trained-to-handle-tense-situations-well calm, completely calm. Emotionally, Luke is very stable; he can move very fast if he must, but he seems unhurried. It’s extremely difficult to throw him, though it can happen. All the same, he feels more alive in emergencies.
He’s gracious, courteous, humble, and personable, even to droids. He hates to “pull rank” in any way, though he will if he must. There’s an assurance to him, and a quiet good humor. Luke is not threatening. Not unlike Obi-Wan, one of his default expressions is a faint, gentle smile.
Still, there’s a sort of heaviness to him. A touch of responsibility and old sorrow which are linked and never far from his thoughts, a degree of reserve; he is mildly inclined to depression. He has the kind of deliberation you’d see from someone who’s around a great many delicate objects, is aware of their fragility, and is very conscious not to break them. Luke’s got an inclination towards depression and something of an old soul. Put him in the Force-negating field of a ysalamiri and this oldness largely evaporates, making him seem more energetic and optimistic.
Luke is quite calmly ready to die rather than turn to the Dark Side. To the point where, in a fight, if his only options are tapping into darker emotions to survive or letting his opponent kill him, like Obi-Wan did on the Death Star, he will pick the latter. His views on death have changed. A Jedi does not fear death, but welcomes it as an old friend; those who have died are one with the Force. Not that he won’t grieve, but it’s without despair.
Luke’s highly attentive to romantic partners, and firmly believes in communication. People he finds attractive do end up in his blind spot a little.
There have been times when he’s been a bit of a showoff. He isn’t anymore. Luke is reluctant to casually use most powers, beyond mild telekinesis and the Force as a sixth sense. He’s also a big fan of free will, and has come around to the point of view that sometimes you must let people struggle through things on their own. If he can ask for permission to do something to someone, he will.
Between his reluctance to use great powers, his calm, and his conscious efforts to be passive and let the Force guide him when there is no plan, he can sometimes come off as ineffectual and out of touch.