Stay out of the Fire Dragon's range. It has a range of three spaces, the same as a longbow. Hopefully you had the foresight to transform your other lords into their respective second class character. (Lyn - Blade Lord and Hector - Great Lord). Lyn's Sol Katti, given to her by Athos, was fashioned for dealing with Wyverns; therefore, it can actually deal some damage to the dragon. If you happen to have Thor's Ire (Nils can use it to raise critical levels), then use it on Lyn. Her critical percentage will be raised and you might get lucky enough to see an incredible show. All of this relies on the fact that you can keep her alive -- HP in the 40's is best). Keep Eliwood a few paces away from Lyn in order to rescue her once she has completed her attack on the dragon. The Elixirs you have will be useful for keeping her alive. Also, a Druid/Sage/Bishop with Heal/Mend can also aid you. Keep attacking/rescuing/healing with Lyn until the dragon dies. This may take some time, but it keeps your company alive. Also, if Lyn is not a Blade Lord, try using Hector's Armads, if he is a Great Lord; do not use Eliwood -- the Durandal may seem like a good idea but for some reason the dragon can attack twice if you use it. Also, you will need him or Marcus to rescue the attacker.