Hello,
1st of all i would like to suggest you to switch ur leona to a patk kain, no offense ofc. I've done extensive tests and I am certain that it will increase your OVERALL dmg comparing to leona (especially now that SoS is history).
2nd concerning ur question there is no definite answer. Giant CD is very good, but you cant be sure u'll get it (it actually increases ur pets crit dmg more than all the items u have on summ combined ^_^) . Nobl authority is for sure a much smaller boost but with no uncertainty. U buy it u have it. It all depends if u feel lucky and wanna risk it.
From my point of view i would try for giant ls (if u can find them on a sensible price). There are a lot of usefull skills u can get like giant cw, cele or hp/cp. If u decide to try giant ls buy a bounch of different Requiem weapons and aug them. From the people i asked most of them got giant CD on dagger or pole, but i believe that might be a coincidence.
@SoRayN
Iss/heal/archer /tyrr u can play with light armor. Supports don't need fancy weapons.
Feoh needs a robe and u can keep ur weapon (but u need to chose what SAs u'll use). It's possible though.
Choose a dual class that can give u access to aoe farm areas!
For max PVE dps
Savage + hurricane shackle (with noble eagle AP, from warrior tree, the one that mentions accuracy). This AP lvls ur hurricane shackle to lvl2 which gives u a buff (that also goes to pets) +10%p/m atk for 60s.