SummonerYuna: Thank you. All of this is very helpful. I actually went to a previous save file just before entering Blacklake District and I am focusing on getting all the possible experience from all the quests (including henchman quests). I think I have an idea of how to do this. I'll try to get my Paladin to level 7 before he faces the swords the again. When that happens, I'll bring Daelan with me (I just leveled him up and did his quest which gave me a nice amulet). I'll buff as much as possible (including a Potion of Speed ) and use a wand of lesser summoning and use the creature as a distraction while I focus my attacks on one sword a a time before they can do too much damage. I'll drink potions of healing as needed and hopefully Dealan and the summoned creature can hold while my Paladin deals the heavy damage.
Have you completely finished all of the other districts? I don't recall the anticipated level progression of the game, so I don't have a good idea of how much material you've implicitly covered. If you haven't finished the other districts, then just use your current save and go adventure in one of them for awhile. You don't have to complete any district before visiting another one.
Some other things:
-You can level a henchman at any time; they don't gain XP in the usual sense. Ask them to level, and if they aren't one level below you, they sit for a moment, then say they've leveled. So feel free to keep Tomi with you until you want to try the swords again, then just go drop him off, pick up Daelan, ask Daelan to level, and head over to the swords.
-You can save/load during fights, similar to how the guy in the video linked above did.
-You can leave the room if you start to get low on resources (hp, companions, whatever), then come back in to resume the fight. Expect any injured opponents to be back at full hp,but any dead opponents should still be dead.
-Check damage types that the swords use during the battle. You may be able to find things that can mitigate or completely protect against these damage types.
-Pre-buffing is an excellent idea, and you should have at least a paladin spell or two you can cast, if nothing else.
-Make use of companion commands to have every person/thing in your party hitting one sword at a time, even if the swords are attacking different members of your party. The faster you kill a sword, the sooner that sword is no longer hurting you.