Skirmisher's Sabre - Devourer ignores Trynd ult

Hello, I recently played a game where we had a yi jungle and the enemy had a Tryndamere top lane. Skirmisher's Sabre - Devourer was the jungle item our yi got and it was able to kill trynd while he was in undying rage. I am unsure if Skirmisher's Sabre - Devourer is the only jungle item/enchantment that does this, but I know for certain that at least this combination does ignore undying rage.

I am sure of the fact that this is unintentional, and should be fixed.