Most of the game wouldn't work well for THL, but if you look at playthrough 1 of the walkthrough, you can see that you can earn 5 trophies between 1/6 and 1/17 with no major event inbetween. You can play until 1/5 and have a save ready when the day 1/6 starts (Save at the location screen on 1/6). It should take about 15 mintues.
I don't remember the sword either lol but if i recall you must've gotten Eltricia and Ist right since they are the ones mentioning a sword in that area. Cause the dungeon there you need Eltricia to continue on a certain part of the dungeon since it requires a royal blood to pass through the door but stays open once you do. Hope that kinda helps? xD