Ewer: Either a healer or BRD if you absolutely don't need it at all and RR would be a waste/bait. You can use it on SMN as well in some cases. Other jobs generally can't do anything with it.

Spear: Any job pre-pull, either yourself (if you plan to use big cooldowns soon and you can work around it), any job you think will use cooldowns soon (and again, can work around it). SMN for Aetherflow, NIN for Ninjutsu/Ogcds, BRD for ogcds and DRG for ogcds. It is a card that is hard to determine which person will benefit most, sometimes the best use could be giving it to a BLM so they can Enochian sooner and avoid awkward downtime between phases.

Bole: Tank or a target you're afraid won't survive a mechanic. AoE Bole is a possibility in case you do end up having it, but don't rely on it.

Spire: Any job that has low TP or can use the TP to AoE better. Generally RR fodder.

Balance: Highest DPS at that moment. Also check who just used burst cds if it is a blank or enhanced Balance, a good bursting DPS will benefit more than a slightly better, non-bursting DPS if the duration is just 30s.

Arrow: Same as Balance, but a bit more constrained since not all jobs make the same use of attackspeed. Would generally put it on a BLM first, otherwise a MNK, then just pick the DPS you think is performing best (generally DRG would be next in line). Be careful since Arrow will cause any TP users to drain TP faster, which is easy to forget. You can also use Arrow to boost your own healing or you co-partner's healing, making it the only card to increase HPS.