Holmgang need a range increase.

[Rhyn]

that is what war pays for a short cd invulnerability......

Hallowed Ground - complete invulnerability for 10 sec.
Living Dead - can't be reduced below 1 hp for 10 sec. I have never seen the walking dead status matter, ever.
Holmgang - can't be reduced below 1 hp for 6 sec. Needs a target. You are immobile and can't dodge that telegraph that is assuredly coming for your face.

There are plenty of downsides to justify the shorter cooldown already. Having the ability straight up -not trigger- when you need it because you fought a boss at a normal distance instead of inside him should not be one of them. Yes that is hyperbole, but I've had Holmgang not trigger so many times at a normal fighting distance.

Why would you even not be within melee range from the boss? I really can't think of any situation where I'd want to holmgang away from a boss.

It's 6y to the center of the mob. While other attacks don't seem to work this way, so you normally fight a large boss outside this 6y range.