I don't disagree with your overall point, but I would quibble with this.
If a weapon caused unnecessary excessive amounts of pain (without any other purpose but sadism), corrupted their minds and/or souls, or enslaved peoples souls after slaying them I would judge that effect to be truly vile in nature. So I believe some effects are unnecessarily sadistic/malicious in nature.
Your idea for the sword is certainly savage and ruthless, but is more reflective of the materials with which we have to work with; rather than a desire to cause undue suffering. It is certainly borderline though. Perhaps the claw would be best used with another reagent to undercut its innate malice without weakening the enchantment?
Again, I'd say intent matters, rather than the effects. While torture weapons can be used for sadistic pleasure of the torturer, they have also been used against criminal and spies to extract important information. The implements have remained same in both cases, and while the former has been universally derided throughout the ages, the contemporary morality has supported their use in the latter case. Even well into 21st century, use of methods of torture like waterboarding and such have been institutionally supported by countries that are judged to be free and democratic. Ultimately, modern morality abhors all uses of such tools and techniques, but morality should never be anachronistic. By the dictates and popular sentiment of their time, use of such
evil weapons against the enemy spies and criminal was considered justified. Therefore, to judge a tool as evil is ultimately wrong, it is always the wielder who determines how it is used and intent that determines how it is perceived. 'Tis a bad workman that blames his tools, after all.
Now of course, there are some weapons, like Widowmaker or similar weapons, that exert a influence on the wielder and make him more cruel. But comparing them to a simple enchanted sword is comparing things vastly out of comparison.
Is the design I proposed vicious? Of course. But remember, most popular bullet for hunting, the soft-point bullet, is banned for warfare, because of the viciousness of the wounds it creates. Therefore, even vicious things have their own use. Strike the enemy as hard and as cripplingly as you could, that you may spare your allies from sorrow. A weapon better designed to kill and maim the forces of Chaos, Undead, Druchii and Orcs is a good weapon in my mind. And the design I presented were, I thought, closest in nature and conception to the original materials and hence better suited for enchantment.
Like you are free to propose new enchantments, but I will not say my proposal as borderline
sadistic.
People can be sadistic, cruel, evil and vicious. The weapon, if ever made, would be just a hunk of keratin if no one were to use it.