Why is verbal weighted more heavily? Should I retake?

You do not average your two scores to determine your overall percentage. Think about if you scored 90% in verbal and math. This means you are better than 90% of everyone in verbal and 90% of everyone in math. But, assuming no correlation between the 2 sections, this means of the 10% who are better than you in verbal, only 1% is also better in math. The correlation would not be 0 but also would not be one, it would be somewhere in the middle, if you are good at one section you are probably better than average at the other, but usually not the same exact ability.

If you do 50% V/50% Q, you will be 50 % overall. If you do better than 50% in each section, your overall will be higher than your average. If you do worst than 50% in each, your overall will be less than your average.

Second question, from my research it seems top schools put a check mark next to gmat if you score in their range. You should def have that check mark. However, if you are looking to go into the fields of finance after school, especially I banking, a high qaunt score (48+) is something they look for.