Dragongrief
Explorer
I think it's best used by a Moon druid for the times they don't want to waste a transformation (kobold or goblin warrens). They should probably have the War Caster feat anyway, because Barkskin + Bear form is a thing.
There are also "stealth" uses - cast the spell before walking into a negotiation that you expect to go wrong quickly, and then "drop" the blade. If/when things go wrong, you can re-summon it as a bonus action and attack or cast a non-concentration spell on your first turn.
*Edit: Throw on Hide armor, a shield, and Dex 14 for a decent AC (16).
There are also "stealth" uses - cast the spell before walking into a negotiation that you expect to go wrong quickly, and then "drop" the blade. If/when things go wrong, you can re-summon it as a bonus action and attack or cast a non-concentration spell on your first turn.
*Edit: Throw on Hide armor, a shield, and Dex 14 for a decent AC (16).