A DA is your best bet, unless you are brave enough to try the heat gun method, which has been posted a few times on VWROC but I don't know anyone who has actually done it themselves, they just post the video but never try it, lol. Even with a DA it can require something with a decent bit of cut depending on the level of etching, it doesn't always come out with a finishing pad and polish. When I polished my car at Easter some of the bird poo etching required a good going over with a cutting pad and compound, before refining down with finishing polish and pad. You can try hand polishing but it will probably give limited results. As Joe has said, I'd be wary of drill attachment backing plates and pads as the level of control is not the same as with a DA and nor do you have the random orbit of a DA which prevents burning through paint as the heat is dissipated via the random action as opposed to a rotary motion whereby heat can build up in one spot.
A medium cutting pad and medium cut compound will bring it out, and preferably followed up with a finishing pad and finishing compound to refine. Meguiars 105 (cut) and 205 (finishing) is a good combo for this and many other polishing jobs, such as B Pillars, bodywork etc.
Sealants, waxes will not stop it happening, and even glass or ceramic coatings offer limited resistance depending on which coating it is.
