I feel like if they were going to go the path of "Well it's a personal buff now" they would have just swapped it to that. "Envenomed Blade", grants 10% increased damage, lasts up to 40 second.

Let's be real though, the actual issue is just that Job HUDs are incompetent. Tracking a 20-40 second debuff isn't hard, it's tracking a small debuff icon that most people don't go out of their way to make more obvious that is. Dark Knight shouldn't be the only job who's HUD tracks the one thing they have to keep up at all times, everyone that has such a mechanic should have one.