Nisan and Attack Aveh
Items found at the Kislev Border: Extra Ar +2, Gold Nugget, Magnetic Coat, Rosesol S
Items found at the Kislev Border Desert: Extra Ar +3, Gold Nugget
Reaching Nisan shouldn't be too hard. Near Bart's Hideout, head North until you find a lonely tree on the desert and click on it to submerge the Yggdrasil. After some scenes you'll be automatically inside town.
Visit the town if you want (There's nothing new to buy except for some nifty acessories; if you can buy an Ether Doubler, by all means, do it!), take a peek at the meeting hall for a scene, then head to the Monastery. The Nisan visit is pretty much for story development...Just follow Margie around, check the painting, then talk to Agnes for more historical details. Go back to the entrance of town and talk to Sig inside the lodge. You can (and should) ask questions about the whole situation and after you're done asking, go talk to Bart on the nearby bridge for another scene, then go to the town hall. After lots of planning, talk to Bart the day when you're ready. After more scenes (Do they ever end?), you'll be controlling Citan, so go talk to Maison, then climb the stairs near to bridge to go outside and watch MORE scenes (Last ones...for now).
You can finally move around with Weltall. Head East, jump the ledges and go back West a bit to get an Extra Ar +2. Now go back and head NorthEast, following the other pirate gears doing a big jump to another ledge, then stop following then and go South/SouthEast to get a MagneticCoat at the other tip of the ledge. Now go back North following the pirate gears heading NorthEast. On the next area, head SouthWest and jump to the Eastern ledges when you spot them (You can also circle around West but it's a longer path) and don't forget to get a Rosesol S to your NorthEast. Continue NorthWest and jump to the ledge yo your SouthWest to get a Gold Nugget. Now keep climbing North until you find a Repair Bot. Take your time repairing and saving, then go North, then East to fight the Gebler units.
The Gebler units are EXACTLY the same from the last battle, so they shouldn't be too hard. The problem is the battle after them, against Vierge. Use Booster and your best attacks and you should defeat her before she uses too many Aerods. After you win there's a scene between Fei and Elly and after that you should refuel, then continue the area, following the obrigatory way until you reach a bright spot. You'll watch another scene with Bart, then we're back on track with Fei.
After some scenes, you'll have to complete a small mini-game. Just keep heading up avoiding enemies and mines (Although they'll barely damage you, unless you stay put for too long). After 2 areas, you'll have to destroy the Kefeinzel gun. If you want to avoid being shot by it, use booster and leave the small guns for later. After some other scenes, you'll have to fight Dora.
The Dora is a bit tricky to defeat. Attack with Weltall only until the Head Cover breaks. Then you can attack with the other gears. Also, using Booster in this battle might save your skin, since Dora can take some decent damage and has high HP. After that, there'll be lots of scenes with Fei, Bart (No, you CAN'T win) and after all those scenes, Fei will wake up in the Kislev capital, also known as Nortune.