I agree that Atma's could use a better recipe, but I don't think your suggestion is a big improvement.
The way I see it, the idea behind Atma's is the same with a big spear IRL. If you put a lot of weight behind it, you can impale someone quite easily even if they have armor, but a small/weak person will not be able to do it even against someone without armor. As such, I think it would be a better idea to change the stats somewhat so that you get only damage and armor penetration from it (not crit), and that those stats scale entirely off of health.
It could be a bit imbalanced on for example Nasus. Not sure. But from a general design perspective, I think it makes more sense. Maybe Atma's could get a new active similar to Hydra? So that you put your weight and throw yourself forward to deal at lot of damage to one champion.
Anyway, I think the recipe should be more like 1 x BF Sword + 2 x crit gloves + 900 gold, and then make it damage/arpen/active based entirely off of health so that it isn't a viable item for ADC/marksmen. This would also define it as a late-game item to turn around fights.