Level 2 (Fearless Blue)

around how many defensive weapons are need to get to level 2 im not sure how many weapons a 75 defensive index contains

Missil interceptor batteries are the most efficient type of weapons to increase index. You need 230 of them to raise your index by 1%, so for example, if you are currently at 10%, you would need to add 65*230 = 14950 batteries.

so 230 missile interceptor batteries will only increase the defensive index or the war index by 1%?

Yes, it will only increase the defensive index by 1% (and the defense index by about 0.5%). The war index is something completly different. I dont really understand how it is calculated.