Is the Hunt the only way to acquire Allied Seals?

[rappa]

Mainly, Alexandrite, more seal equal to less days to complete the scroll

[Niwashi]

I've heard that in a hunt party, helping others with their weekly hunts nets you some seals as well.

The only thing that helping others with their weekly hunts gains you is the appreciation of whoever you're helping (which may be useful if you then want them to help you with your own weekly as well).

Hunt parties are usually about going after A and S rank hunts, which aren't associated with the Daily or Weekly targets. (They don't even require having unlocked the Daily/Weekly Hunt system.) You can go after as many A and S ranks as you can find and take down. Hunt parties usually go from one A rank to another to another to another, getting 20 tomes and 20 seals from each, and occasionally may be lucky enough to find or spawn an S rank as well, which gives even more. Just keep in mind that it generally takes a full party (or equivalent) to take down an A rank and at least two or three full parties to take down an S rank. (Having more than that will make it a lot easier, though.)

[Jamillion]

I have 4 retainers and don't need soldiery gear at the moment so I've been spending my seals on Ventures

[Hyunckel]

You can also buy minions, at least the wonderful Succubus ♥
Pretty sure there are 3-4 others.