Aion's veteran reward system is due for an extreme makeover, and we here at Massively would love to bring you the details. There's just one problem: NCsoft hasn't released any. A cryptic news blurb on the game's official website hints at the changes, and it also touches on the reasoning behind them (apparently the upcoming 3.0 patch is going to make some veteran items obsolete).
Aion players may collect their 28-month vet rewards beginning on January 25th, and claims can also be made in the month of February. After that, though, you may not get another chance since the "current veteran reward system will be discontinued." We'll update you on the situation as we learn more.