The test was done by a GM of Shaiya IT.
Toon 1: war lv1 with axe lv1 linked fire ele1 or fire ele2
Toon 2: war lv5 with top earth lv1 and earth lv2
Each attack was repeated 3 times
1) Fire ele1 vs earth 1 : 39 - 38 - 35 dmg
2) Fire ele2 vs earth 1: 39 - 34 - 36 dmg
The results show no difference, but I was worried the attack was too low to show real effect, so he added 800 str to toon 1 and 800 rec to toon2 (GMs can do it
After this change toon1 had 1073 - 1081 attack and toon2 had 805 defense
3) Fire 1 vs earth 1: 276 - 271 - 270
4) Fire 2 vs earth 2: 271 - 271 - 273
It is evident that ele2 and ele1 vs neutral ele1 have same effect and it is 100% normal damage (considering attack and defense the normal damage is in the range 268-276)
After your reply I asked to repeat the test vs an earth 2 top, here are the results:
5) Fire 1 vs earth 2: 268 - 270 - 274
6) Fire 2 vs earth 2: 253 - 256 - 252
Apparently ele2 vs ele2 do less damage than ele1 vs ele2, same neutral elemnt
This makes no sense tbh, but I made him relog and test again to be sure bless and endurance was ok and the results were the same the 2nd time.