[@Brocktree] The Collective has seen peace for many hundreds of years, but that doesn't mean there has been no need for occasional small conflict. Every peaceful nation needs a coast guard in the case of incursions by small groups, but that doesn't always mean a disruption to the Collective's peace. The Star Guardians have, in the past, been that coast-guard-type force for the Collective. They work with the other branches of the Vanguard, and have faced smaller skirmishes for many years, but nothing that has disrupted the status quo. Individual operators during these skirmishes, especially the Sentinels, would have seen action in these skirmishes, and so someone who's been around for 700 years would have seen many of them, and thus become a Veteran; not of war, but of small theatres of combat over a long period. Hailing from an exile world has nothing to do with it. The exile worlds usually produce the incursions, that those in the Vanguard become veterans of over time.

Edit: Also, just a reminder that we have a Discord where you can find more tidbits of scrumptious lore and info. Link is at the top of the Zeroth post.