How you should think about it is simply in terms of physical security. Not necessarily offense or defense.
The physically costly bits of information secured by proof-of-work can be used to drastically increase the cost of attacking your computer network to the point where it's literally too physically costly for any attackers to even attempt attacking.
A weapon can be either passive or active physical power projection.
A wall is technically a passive physical power projection weapon.
People think in terms of offense and defense.. but the right way to think of it is passive and active tactics, techniques, and technologies that allow you to achieve physical security.
