There is such a simple solution.

Lv 120 trial:
Moogle wants you to prove yourself by bringing back the "Pwner of Delve" KI.

KI is bought for 300k plasm and only available after killing all THREE delve bosses.


Done. Deal. Now the trial by itself is harder than a delve weapon. (Weapons are ONE boss+200k plasm. This requires all 3 and 300k) So now REM can be better than delve weapons because they are harder to get than a delve weapon for just the final trial.

Now Delve people cant bitch about REMs just buying their way to the top and REMs can have their weapons be on top. Make them go through the same system and all the problems are solved.