Can an attacker choose to assign damage to a defending unit with higher might than the attacking unit's damage (e.g., assign 2 damage to a 3 might defender)?

Ruling: Yes, you can assign damage to any defending unit regardless of whether the damage is sufficient to destroy it. Only the Tank keyword and similar abilities force damage assignment to specific units.

Nuances:

• Damage heals at the end of combat
• There is no "under kill" rule that prevents assigning insufficient damage to destroy a unit