You don't need to pick up baggage at POE, definitely not on Etihad unless it's 2 separate tickets (i.e. KTM to POE is one ticket and POE to Final destination is another). In fact, I've never had to collect mine in any of 6 different trips back into the US. Once you've boarded the Etihad Airways flight at Abu Dhabi Airport, your entry will be treated like a domestic flight.