I think this may have been a case of that specific sword simply having wildly inflated secondaries. If I recall correctly, when I played during Wrath, +STR and +Hit were the stat kings for plate DPS classes (I remember all the guides recommending +STR gems in every slot and +STR enchants on everything) and secondary stats were, well, secondary, and inflated secondaries on a weapon weren't that big a deal. But now that secondary stats have so much more importance, I suspect that an "outlier" weapon like that just wreaks havoc with modern calculations, so that all the addon sees is that this particular sword offers +15 more Haste and Crit than everything else that drops. 

Workaround as a player is simply to skip forward past that step in the guide, at which point it has steps for the other quests. I'm still on Bleakrock as that character, so I don't know if a duplicate "begin the evacuation" step exists after you've found all the missing people. In either case, just don't talk to Captain Rana about evacuating until you've completed all the other main/sidequests on Bleakrock, which are listed at the UESP link above.

What am I supposed to do now? Is there a way to get the curse client working again? I've googled it but haven't found any useful results. Do I have to uninstall & re-install it from scratch? Has the Curse client been taken permanently offline, meaning that it's no longer viable software? Do I have to install a Twitch client and manage my WoW addons from there? If so, do I have to re-install all my addons from scratch, or will they somehow carry over from Curse to Twitch?
I also wanted to note that a lot of users, I found on the Web claimed Dugi’s Guide to be faster.  However, all these users had either used Zygor Guides for very little time or had not used it at all.  I have to give a point to each Dugi’s Guide and Zygor Guides as they both deliver a great lvling speed.  For all you Dugi’s guide users out there who really feel that Dugi’s Guide is faster, I will give Dugi an extra  point.  If there really were a difference, it wouldn’t be by much.