the most important things, beside reasonable weight, are a sharp broadhead, and excellent arrow flight..
Excellent arrow flight definitely. Hence the high FOC. That helps give excellent arrow flight.
But you can't 'just' add more weight up front. You have to plan it out first. Knowing how much weight you want up front, is a key step to figuring out what spine arrow shaft to use. The FOC calculator at Jackson's is a good tool for building cyber test arrows and playing with FOC values.