LE Enemy Involnerable except to specific weapon kind

[stormshallow]

Attention Advanced Modders

I'm trying to design a system whereby an enemy is invulnerable to
all attacks except specific swords, and the enemy weapon can ignore
any armor except a special kind. The enemy also needs to be immune to
magic attacks.

I need there to be no effect when advanced 5000 damage weapons and
spells are used on these keyword enemies, but a SPECIFIC 25-50 or so
damage sword can effect the enemy just like it would any other enemy.

I've tried creating this in the Creations Kit, and can't get it.
I'd prefer not to use a script, but I will if I have to. If someone
could build this system, and release it with instructions as a
modders resource, I'd really appreciate it, and I'm sure many other
modders would also. Any advice would be helpful.

Thanks for your time.