Initially noticed this in a Standard Brawl game.

Problem:
Danitha, Benalia's Hope enters and brings the Aetherspark into play.

Expectation:
It should be equipped to her.

Result:
Nah.

Reproduction and further experimentation:

I've only tested standard legal cards.

Cards that equip the Aetherspark to a creature you control:

(Stipulation: Astor, Bearer of Blades is not on the battlefield)

Weapons Vendor
Blacksmith's Talent
Kemba, Kha Enduring
Zack Fair
Raubahn, Bull of Ala Mhigo
Rhuk, Hexgold Nabber

Cards that do not equip the Aetherspark to a creature you control:

One Last Job (returns, does not equip)
Magnetic Snuffler (returns, does not equip)
Danitha, Benalia's Hope (brings into play from either hand or graveyard, does not equip)

Stipulation - Astor, Bearer of Blades is on the battlefield:

Previous cards that worked without Astor on the battlefield work.

One Last Job, Magnetic Snuffler and Danitha, Benalia's Hope now equip the Aetherspark successfully.

Urgency of the problem:

Who even knows any of these cards aside of the Aetherspark? :^)