Actually, come to think about it, there's quite a few weapons that will shine, but yes, they're magian trials only. No weapon is decent outside of trials at level 90 with the obvious exceptions, but I'll list a few from trials, not considering relic/empyrean/mythic (I shouldn't even say mythic... anyone who melees with Yagrush is doing it wrong and is capable of getting a much better weapon for meleeing. No one would doubt Yagrush being amazing in general, but for meleeing, it isn't).
Canne de Combat +2
DMG:71 Delay:310
"Dagan"
Dagan discussion aside, this is the 5th highest base damage club in the game, with the lv85 empyrean having 74, lv85 relic having 76, lv90 empyrean having 78, and lv90 relic having 81. However, a lv90 Naboot +2 with the DA+ would likely outperform this overall, although more time consuming to get.
Naboot +2
DMG:58 Delay:340
Occ. atk. twice
I know a lot of people have liked OAT weapons from magians in general, however, this is a case where I'd probably say the Double Attack+ club is superior for a main hand, which I'll list under OA2-4x. Although, yeah, it's better than any AH option you'd get.
Naboot +2
DMG:33 Delay:340
Occ. atk. 2-4 times
A decent offhand in my opinion for one who lacks a kraken club, given TP feed is favorable. There's times where feeding too much TP can be a bad thing, but overall, this would probably be the 2nd best offhand for someone with relic/empyrean, with KC being the best of course for TP gain and Hexa Strike/Mystic Boon spam.
Naboot +2
DMG:70 Delay:340
"Double Attack"+10
I would have to say this path is one of the best non-relic/empyrean clubs in the game right now. The DMG rating is HUGE, and it's only behind the WoE path/relic/empyrean clubs when it comes to sheer base damage. If you're aiming for a relic/empyrean, I probably wouldn't do one of these and seek an offhand version. Of course, I probably also say that because getting one of these is easier than getting a kraken club.
Hoeroa +2 (STR Path)
DMG:47 Delay:210
STR+9 Attack+20
Now the damage rating on that is lackluster compared to the other options, but the delay is very low to compensate, almost as low as a club gets.
Now looking at the "top" weapons:
Mjollnir (90)
DMG:81 Delay:308 Attack+35
"Randgrith"
Additional effect: Recover MP
...Do I even have to say this is our best melee weapon?
Gambanteinn (90)
DMG:78 Delay:300 HP+70 MP+70
"Dagan"
Aftermath: Occ. deals double damage
If only Dagan did damage, it'd be more worth seeking. Fun to play with aftermath I'd imagine though. The proc rate is definitely far more frequent than relic's multi-damage procs, but to give up a lot of damage to use it in the first place...
Yagrush (90)
DMG:63 Delay:267 Magic Accuracy+20
Augments "Divine Veil"
Enhances "Divine Benison" effect III
"Mystic Boon"
Aftermath: Increases Magic Acc./Acc.
Occasionally attacks twice
Yeah, I'll list Yagrush, because it does have respectable damage for the delay. However, it easily falls behind most options. Good thing it's useful for the back-lining part of WHM.The potential is better than Gambanteinn in a sense, but likely not as well, as unlike Dagan, Mystic Boon does damage, but you have to get 300% TP to trigger OAT. However, I think it'd make more sense to go after a better main weapon when it comes to meleeing, because you'll have Mystic Boon even without Yagrush.