Armed vs unarmed is not a definitive factor in a self defense case. The criteria are that a defender who 1. reasonably believes they face a 2. credible, 3. criminal, 4. imminent, 5. threat of death or grievous bodily harm, may use any level of force 6. necessary to stop that threat.

Reasonable belief, credible threat, criminal threat, imminent threat, sufficient threat, necessity of force.

An unarmed attacker can, indeed, generate all six criteria required to justify lethal force in self defense.

The jury doesn’t seem to think that happened in this particular case, but it certainly can happen and has happened. Please don’t repeat that nonsense that it can’t.