Hearthpwn

Mistermath's Card Ratings for Voyage to the Sunken City:

6/10

Ah, simple ratings. A 3/2 for 2 with a pirate tag is about a 4.5, and this gets a nice point-and-a-half bump because it acts as both card selection and preparation for future turns. Unsurprisingly, this card is good enough to make it into pirate warrior, and is solid in arena, too.

how is this better than the legendary?

This is tutor for Azsharan Trident. And doesn't conflict with quest at all. Quest draws the base weapon, this minion gets the Sunken Trident with +1, +1. 

Lady Ashvane doesn't seem that bad now even without a pirate tag.

Doesn't seem that great. Hitting a minion is just bad and hitting a weapon is too inconsistent, but I guess the quest needs some support to still be relevant.

Minion or weapon basically guarantees you'll hit something.  Good card.

most of time you probably won’t dredge weapon because of quest, unless you wanna remove or trade minion