I'ts really simple the answer is just in front of you the entire time. Just get rid of the soft cap and make . blues and purples dropped at your current level than you could round off your build and use mile stones to level up. If you suffer from a rng based level system than how pissed do you think ppl like me got , when i had 3 power weapons drop from my mile stones and did not increase my level a bit . I'm sure you have heard this before . but this way you could keep your cores for masterworking. And keep them scarce to make master working a "impactful choice"