

When it comes to basic armament it’s all about coating yourself
When it comes to techniques
- Basic invisible version
- Hardening

Then there’s external and internal armament


External being the second level allows you to focus the haki not just on your body but outside of it
Along with just strengthening your attacks and defense in general it also allows you to coat your weapons in haki. Something zoro was able to do pre timeskip even with his unsheathing techniques like lions song and rashamon. Tho he obviously mastered that step during the timeskip

The hardening version of external being able to actually harden things outside of your body like weapons

Also while yes you can use external armament to create invisible barriers defensively but that isn’t the only use

When it comes to internal armament we’ve only really seen it used offensively. We have yet to see how it helps defensively or how hardening is applied
- When it comes to armament I imagine instead of just coating the outside of a weapon it’d coat the inside too making it even tougher
- Defensively idk tho