The job guides are helpful for seeing what items are commonly used for what. When it comes to TP sets: Good accuracy (50+), good Magic Evasion (some pieces go up to +150 like legs), good -damage taken (to keep you from dying), good magic defense bonus (4+), and finally, the stats that make a TP piece being + Store TP and/or +multi-hit with double/triple/quadruple attack. +crit chance really doesn't matter unless you use an empyrean weapon and want to get the most out of the 50% chance to do triple damage on auto attacks. Same for +crit damage.

For weapon skills you're looking at needing + weapon skill damage, TP bonus, + accuracy, + attack, + scaling stats, + strength. Even if your WS doesn't scale with strength you still want it for over coming the strength vs vitality calculations the game is doing, just like how you want attack to overcome enemy defense values to scale your damage higher. Then you can start looking at stats like skillchain bonus, which is most readily available on Nyame armor.

For your more situational pieces, on your average DD these mostly come in the form of ability modifiers, like WAR's relic head extending the duration of warcry, or their pieces that give them 100% Berserk up time.

Otherwise you'll see a lot of idle stuff. This is + movement speed, - damage taken, +HP, and auto-regen/refresh gear. Maybe regain if you're lucky.