I think we all agree that Mach+ is for endgame only and completely sucks for EXP, so everything im saying is geared towards endgame.
Personally, i really hate this sword. I really really dislike it.
For everything you can hit, a company sword for example has a 150% increase on the DMG rating alone. (37 * 1.5 = ~56). That's a 150% increase on hate gained through melee hits. More than weights up against the 4% increase in my oppinion.
150% of 0-10dmg is still absolute crap and will not increase your hate by any noticeable amount.
I understand you cannot hit everything for decent damage, like gods for example, but 4% enmity is nothing. A paladin already has plenty of enmity. And when was the last time you actually went all out on Enmity gear anyhow? Wore that Adaman instead of your Gallant Coat? Used your Hercules ring instead of Jelly/BQ/or anything else?
You're right, 4% enmity is nothing over all. But if you think like that with every piece of gear, then you're going to lose out on a lot of enmity, enough so that there will be a difference. Just by looking at the piece you bring up, you're losing out on 8 enmity.
Adaman body is still just as good as Gallant if not better, and imo if you already have around 1500 HP, then the extra 1% enmity from adaman will work out better for you than 20 HP. But honestly, thats a piece that can go either way.
And please don't get me started on Jelly ring. You should absolutely be using a Herc over that piece of crap considering the main thing that will be getting through your shadows is magical AOEs. The only thing people wearing jelly rings at fafnir and cerberus and pretty much any end gamefight are doing, is increasing the dmg they take, and decreasing their enmity.
If 4% Enmity suddenly helps you keep hate where you could not before, then you have more to worry about than just your weapon alone...
(That doesn't mean you shouldn't wear it for big kiting fights where you have nothing better to do though... Then again, there -is- that Earth Staff)
4% in one spot wont do much, but 4% here, 4% there... it adds up.
And as far as Earth staff.. there is also /nin. You shouldn't be getting hit much (if at all) while kiting. So load up on enmity.