If it isnt you asking the question again, I think you will find that this matter was previously raised here on the forum, the official response was quite remarkable.

After posting, I think the previous question may have been more specific  with reference to special items.

However I think you will find  that there is a lot of hype in the game seemingly promising much and yet actually giving very little.

It all depends on what you believe, what the maths really does, and where you are in the game, ie what level in various categories.

Its the kind of thing you are either told, assume, or find out later and are disappointed by the reality.

For example 100% improvement sounds fantastic, but what is it a 100 % of ?

If you have already eaten 90% of the cake,  100% of what is left isnt going to much of a  mouthfull.

Curiously battle mechanics are little researched.  Perhaps we (the community of Vikings players) are a lazy lot.

This is the best resource available.  It is hard going and I am not sure you will emerge with an answer to your conundrum.  But it has two thoroughly helpful concepts to take away if you have the patience.

https://www.youtube.com/watch?v=kNaYFgml9IQ

lots of good points in that video confirming other things i have learned. I always change my gems for best results and maxing reducers.

I made some screen shots of my attacks adding boosts and reducers.

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No Buffs 

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with 50% defence added

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with 50% attack added

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35% attack reducer added. Included influence to show its not same screen shot

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35% defence reducer added

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35% health reducer added

According to Nick Matveev in that video the attck on defence (and the defence on attack for that matter) are applied in the first stage of the calculation which establishes the larger army and hence the winner of the battle.  I have not understood his "health pool formula" which he establishes is used in the second stage - the calcularion of the attacker's losses.

Your test - being limited to one highly specific set of circumstances - is insufficient for your sweeping conclusion.

Did some tests with my shaman skills and gear with only defence on them without any changes in kills during attacks. Heres some screenshots with shamen skills defence during attack and attack during attack added. Aslo tryed 500% defence buff with no changes.

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baseline

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Shaman skill 20% defence during attack added

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Shaman skill 20% attack during attack added

 Unless you are talking about another post that got you auto banned, I must be missing the reason for the ban.

I did a search for the post I mentioned. 

Its not a recent post and its a different name.

Here is the link.

https://plarium.com/forum/en/vikings-war-of-clans/583_technical-support/209921_military-bosts-don-t-work-in-some-cases/

You can read the whole thing , but this is what struck me at the time of reading.

I was disappointed again, when support replied me back confirming that this case was in line with inherent game logic, even more, your support team officially says that you sell boosts in bank offers/packages for real money, but these boosts may not work and it’s essential. 

I also found this link ,on perhaps a similar theme. but about marching speed ups. 

https://plarium.com/forum/en/vikings-war-of-clans/583_technical-support/216473_marching-acceleration-does-not-work/

What I was trying to say in my previous response , was that if you have done knowledge research or  have other boosts running from other game areas, then the boosts you are talking about could be so small that they are almost imperceivable, even though 35% would seem to be significant, if its only 35% of a small number, or of what is left that can be further reduced, this might explain why there appears to be no change in the numbers you saw.

In the post your refering to i was applying 35% Enemy Troop Reducers. These buffs are very important and make a noticeable difference when attacking and defending. I did my tests on maxed players, cant say they have no attack to reduce.

But i find it odd that in numerous tests the Offence reducer does nothing when attacking and the Defence Reducer does nothing wile defending. If you trying testing yourself you will find buffs that worked years ago no longer work in the same way. 

To me sadly the whole thing with attacks has seemed stupid since I started. as regularly 12 figure characters go hunting people barely in 6 figures.   It does not make people want to stick around and why constantly I see more people leave than stay, especially with tile hitting till your that far in the red receiving as the same few people stalk you around the board to grief.   

Is generally the same story no matter how much you are training your people, you see 100-1000 troops listed as a fraction of your strength, killing you and when you look at it on paper you wonder why..

Its an old complaint, but yet so true.

There are many reasons for this, one of them is beause they are not going to get so much from someone of similar status , even if they manage to catch them napping, another is because they can, and many a mickle makes a muckle.

The game has changed so much and allowed, in fact I would say encouraged, this sort of thing to happen.   

 Some aspects of the game are so cheap to them ,there is little negative consequence of this behaviour.

Well is no real gain most of the time, and could just be farming the same sort of tiles, without growing a bill to ressurect soldiers.   Now is more like griefing as you say, because no one cares and no consequences

Did tests in defence to show what different gems & runes do all legendary. No buffs used on both sides. 

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Gems: Health 12%, Health 10%, Attack 10% Rune: Attack 32%

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Gems: Health 12%, Health 10%, Blank, Rune: Blank

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 Gems: Health 12%, Health 10%, Defence 12%, Rune: blank

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Gems: Health 12%, Defence 10%, Defence 12%, Rune: blank

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Gems: Health 12%, Health 10%, Defence 12%, Rune 9% mele defence Steel Vortex

Health works slightly better then defence. 

One thing to note Cavalry have a rune: Apeal to Gods, 9% total health, 9% Cav health. Nice bonus on defence.

Heres some attack tests showing (maxed Helheim & skins) OS vs normal attack. Different OS bonuses vs troop types will change results. Using all OS & attack Bonuses in lvl 70 hero skills, special skills.

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Gems: Attack 10%, Health 12%, Health 10%, Rune: Attack 32%

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Gems: Attack 10%, Attack 10%, Health 12%, Rune: Attack 32%

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Gems: Attack 10%, Health 10%, Health 12%, Rune: Attack 32%

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Gems: Attack 10%, Attack 10%, Health 12%, Rune: attack 32%

Thank you for sharing those Britanic.