Not too bad, but I wanna point out few things that caught my eye. ( Sorry if I'll sound dick-ish )
Why is a 25 year old guy considered a veteran? 40k humans have a well expanded life-span compared to ours and even people of 50-60 years are considered relatively young. Not that it matters that much, but just pointing it out.
It says he is a 25 year veteran, not a 25 year old veteran. So, he's been an Arbiter for 25 years.