It means he (paranoid man) has taken it upon himself to guard the angels (people he wants to protect ie...his family) and 'they'll' (anyone he thinks would inflict harm upon them) will get what they deserve (with his rifle).
...
He was trying oh-so-hard to put it into words on the band's forums. I love how they randomly post.
As explained by Ian himself:
It means he (paranoid man) has taken it upon himself to guard the angels (people he wants to protect ie...his family) and 'they'll' (anyone he thinks would inflict harm upon them) will get what they deserve (with his rifle).
...
He was trying oh-so-hard to put it into words on the band's forums. I love how they randomly post.