Questions regarding War Cry (2H)

1. How much ATK+% given per War Cry's level?
2. Is more level = longer duration?
3. Is it worth getting it to Lv10? Or just keep it at Lv1?
4. Since War Cry counts as a support skill, does spamming it (at Lv10) beats actual support skills? You know, to get the rank...

Sorry for being a noob.

I appreciate any input.

 

+1% per level and another +5% if you're using a 2H (+10% at level 10 and +15% with 2H)
The only factor that increases duration is using a 1H sword (from 25 seconds to 50 seconds if I remember correctly)
I personally think it's an awesome buff, so lvl 10 is more than welcome.
And yeah, it does affect supporter rank (my only way of achieving it q.q)

 

Thank you very much for replying! ^-^