I think I have come up with a technically not homebrew solution to not being able to give Soulknife rogues magic weapons in any satisfying way.

Fighting styles gained through DM feat gift of Fighting Initiate based on competing changes in game, which roughly result in the equivalent of a +2 weapon (+4 damage).

Please can you help me refine the changes and wording:

Thrown Weapon Fighting Quest:
[ ] ‘Repetition is the mother of all learning’. Spend at-least two hours a day for a week practicing with Thrown Weapons.

[ ] ‘You’ve gotta get tactical’. Disarm an enemy using a thrown weapon fives times. (A creature can use a weapon attack to knock a weapon or another item from a target’s grasp. The attacker makes an attack roll contested by the target’s Strength (Athletics) check or Dexterity (Acrobatics) check. If the attacker wins the contest, the attack causes no damage or other ill effect, but the defender drops the item.
The attacker has disadvantage on its attack roll if the target is holding the item with two or more hands. The target has advantage on its ability check if it is larger than the attacking creature, or disadvantage if it is smaller.)

[ ] ‘Pressure makes perfect’. Hit an enemy in the following circumstances with a thrown weapon attack in deadly encounters:
•At the maximum throwing range.
•While within 5ft. reach of a melee enemy.
•In 3/4 cover behind an ally.

Duelling Quest:
[ ] ‘I could do this with one hand tied behind my back’. Keep one hand tied behind your back for a week.

[ ] ‘Make your mark’. Win a fight solo against an enemy of equal or greater challenge rating than your own level

[ ] ‘Establish your superiority’. Mark an enemy and then hit them with the free opportunity. Do this attack five times. (When a creature makes a melee attack, it can also mark its target. Until the end of the attacker’s next turn, any opportunity attack it makes against the marked target has advantage. The opportunity attack doesn’t expend the attacker’s reaction, but the attacker can’t make the attack if anything, such as the incapacitated condition or the shocking grasp spell, is preventing it from taking reactions. The attacker is limited to one opportunity attack per turn.)

I would introduce this concept through an in game book, here is my little blur:

Taken from the chapter ‘Challenges to make one fight with style’ in Durnan of the Yawning Portal’s best seller: ‘Did you see that? A guide to advanced fighting techniques for the initiated’.

 Edit: For example in Curse of Strahd after a combat where Ireena Kolyana attempts to throw daggers to help the party:

Ireena approaches book in hand (‘Did you see that? A guide to advanced fighting techniques for the initiated’ by Durnan of the Yawning Portal)
And asks the Rogue character for help in throwing daggers after her experience in the last combat.

She briefly shows some of the contents and though unconventional, the contents exercises and challenges appear to be hard earned and somehow infused with wisdom and experience.

She is obviously nervous that you would be dismissive. and is waiting to see how the player responds... if they respond encouragingly:

Ireena opens the chapter ‘Challenges to help one throw with lethality and style’ and asks for help completing the challenges together.

The first section is on hitting a target in a vital spot to improve damage:
[ ] ‘Repetition is the mother of all learning’. Spend 48 hours over a period of 6 days or fewer practicing throwing weapons at targets.
[ ] ‘To put this into practice you’ve gotta get tactical’. Disarm enemies five times using a thrown weapon. (A creature can use a weapon attack to knock a weapon or another item from a target’s grasp. The attacker makes an attack roll contested by the target’s Strength (Athletics) check or Dexterity (Acrobatics) check. If the attacker wins the contest, the attack causes no damage or other ill effect, but the defender drops the item.
The attacker has disadvantage on its attack roll if the target is holding the item with two or more hands. The target has advantage on its ability check if it is larger than the attacking creature, or disadvantage if it is smaller.)

The second section is on focusing all your energy and balancing your whole body to gain momentum with one arm:
[ ] ‘Get to the point you could do this with one hand tied behind my back’. Keep one hand tied behind your back whilst adventuring for 48 hours over a period of 6 days or fewer.
[ ] ‘Make your mark’. Win a dual (solo fight) against an enemy that will challenge you using everything you have put into practice (a fight of equal or greater challenge rating than your own level).

You feel like if you can complete these challanges with Ireena then you could achieve greater impact with thrown weapons.