That is the trick though, works for me. Leveled up 6 of them to level 5.
What I do is wait for a fight with a hero who already has a substantial stack of creatures. In a fight vs. the Inferno it leveled up one dynasty weapon from 248 xp to max. I increased all enemy stacks higher than mine and also hit num 8 for the enemies until i narrowed it down to one enemy stack.
Usually pick a ranged enemy because that is less aggravating. I just played and had 2 leveled to level 3 in no time. Dunno why it doesn't work for you anymore.
--------------------------------------------------------------------------- never look down on anyone, only to help them up.
I just tried it in Hotseat. Had a hero with 50K Fate Weavers and another hero with 50K Celestials. I made them fight eachother but only gained 380 Weapon XP after the fight. I'll try 1 Weaver VS 50K Celestials and get back to you.
EDIT #1: Nope, same outcome, got about 600 XP. Didn't try it in Campaing yet though.
EDIT #2: OK, I figured it out. What I was doing wrong was making the creatures fight. I tried the 50K Weavers VS 50K Celestials again, but this time I only had the Necropolis hero on Auto Attack and I only defended with the Heaven hero. This way I killed all the Celestials without any casualties, I instantly leveled up to level 30 and my Dynasty Weapon went from 900 XP to Max XP.
PS: I'd like to thank you for starting this thread. I was so lazy to try and troubleshoot the reason why the exploit wasn't working anymore. Now I have every single Dynasty Weapon in the game up to max XP.
Here's a little guide on how I do it.
1) Go to My Dynasty Heroes. If you want to upgrade a Might weapon pick a Necropolis Might Hero, If you want to upgrade a Magic weapon pick a Necropolis Magic Hero. I usually get Sveltana for Magic and Moander for Might. Equip that hero with the weapon you want to upgrade.
2) Start a Hotseat game. Make sure that the "Dynasty Bonuses" option is enabled (by default it's not) and that Quick Combat is Off. The map that works best is "A Bridge Too Far" because it's very small.
3) Press start game and chose the Necropolis hero you assigned the Dynasty Weapon to as your starting hero. For Team 2 add a Human Player (very important, don't select AI). Start the game.
4) Use the trainer to add some resources and build a Capitol and the Spider Sanctum. I use a Cheat Engine script that allows me to build everything in a single day but you can just press end turn, it takes 5 days to do this. Buy a Fate Weaver.
5) Repeat step 4 for Team 2 (it doesn't matter what faction it is as long as the Champion Unit is melee).
6) For both teams increase the number of Champion Units. There are two ways to do this: a) start a fight with any neutral on the map and use the "Massive Army" option in the trainer; b) start a fight with any neutral on the map and use Cheat Engine to increase your troops during the battle (you still need to use the trainer to make the values change fast). The second way is faster because you can enter any number you want. I usually go for 50K or 100K.
7) Make the two heroes fight eachother. On the first turn of your Necropolis hero use Dual Form on the Fate Weaver and then press the Auto Combat button. With the Team 2 Hero you must only press the Defend button (do not use Auto Combat for Team 2).
8) This is it, you won the battle with no casualties, leveled up both the hero and the Dynasty Weapon equiped to max XP and (a very important side effect) you gained a ****load of Dynasty Points to spend in the Altar of Wishes.
IMPORTANT: Saving/Loading and repeating the battle does not work, you do not get any more Dynasty Weapon XP even if you switch weapons. You have to repeat steps 1 through 8.