Relic weapon.

[Kietsu]

The scholar relic is good even at lvl 59 since scholar weapons from new dungeons are useless if you meld the relic with crit.

They nerfed the hell out of secondary stats, crit included. 50 crit reportedly boosts your crit rate by an astounding... 1.165%
Meanwhile, the level 59 codex has 14 more Mind than the Last Resort Zeta. That's not useless.

At any rate, once you hit 60 you can just toss your old book out, and hitting 60 is faster and cheaper than getting a Relic together.