Adding nicer fonts to your terminal vim is not as easy as one would think but here is a good path to follow to make it happen on a mac
brew tap caskroom/fonts brew cask install font-hack-nerd-font
set encoding=utf8 let g:airline_powerline_fonts = 1
And then change it on iTerm2
This has been shamelessly ripped off from here
Now look how beautiful it looks with airline!