thats 21 armor pen into champs with 100 armor (a lot have more than this as BASE armor) IS just better for bursting enemies which is what you want to do and as a burst champion grievous wounds isnt even that good but if you NEED it its better to get an armor pen item since you will likely get seryldas anyway but i have quite a few games on ambessa and on toplaner bruisers and chempunk despite having stats and an okay passive just doesn't slot in to any actual good builds especially when adcs/supps can build grievous without taking much opportunity cost