when you rename a file, (for instance add .sav to it, ie "history.dat.old"), maxthon will no longer be able to use it, and will recreate a new one by syncing with the online history. If the new file is the one you need, you can delete the old one, if not, delete the new and restore the old one by removing ".old".
lastabs .dat files are the last session files, they are not history files. At this point I can't help more, I dont know exactly what other files are for. Maybe 7Twenty or Joemax know ?
unfortunately, if nothing works, then you must accept that you lost a part of your history, rename the whole folder, and sync your online history. Online history stores the last 2 weeks ( by design)