[Snake]

Basilisk Skull
Can Enchant: Weapons, Hands
Enchant Info: 
Weapon: Weapon gains the Alterated tag (-10% main stat scaling), but On Hit: Inflicts or powers up Lingering Damage (Poison) (LV 2, 2 rounds, max LV 100, +2 LV if weapon is made of an Acid material).
Hands: When you use Grapple on an enemy, you attempt to inflict them with Poison (LV 5, 2 rounds).
Both: +2 Acid ATK

Salamander Tail
Can Enchant: Weapons, Hands
Enchant Info:
Weapon: Weapon gains the Alterated tag (-10% main stat scaling), but On Hit: Inflicts 20 armor-ignoring Fire magic bonus damage. +10 damage if weapon is made of a Fire material.
Hands: When you use Grapple on an enemy, you attempt to inflict them with Burn (LV 10, 2 rounds).
Both: +2 Fire ATK

Oni Wine
Can Enchant:
Weapons
Enchant Info:
Weapon: -5 Power. Physical damage dealt by this weapon drains the target's life essence, typically in the form of blood, and stores it by applying Blood Taken LV X (X = 10% of damage dealt, 3 rounds. If weapon has a Vampiric property or scaling tag, +15% instead).

I don’t think either enchant comes close to Oni Wine in terms of general usability. The solution? Don’t nerf Oni Wine—buff the others so they can actually compete with Fated or Reaver.

Enflamed Weapon: Add 25% of Fire ATK to the base 20 damage. If the weapon is Fire-type, boost that to 50%. This does not seem to ignore resistances, absorption, and all other things that make fire unappealing, so tacking on low damage on top of it is overkill on "making this tame".

Envenomed Weapon: Make it apply 5 Poison LVs per hit, from 2. If the enemy disengages, the damage is gone anyway. And this is Lingering Damage, not Poison itself. It does not chunk from Max HP.

Grappling (Hand) Effects:

• Burn: Inflicts LV15 Burn for 2 rounds, plus a Lingering Fire Damage effect for 5 rounds. This lingering damage increases by 15 each time you grapple, up to 75 total if applied consistently. Duration doesn't refresh.
  
• Poison: Leave the 2-round duration, but raise the level to 30 to justify it.
  

Also, keep in mind that Grapple has cooldowns and its hit chance isn’t affected by your stats or the enemy’s evade, so stacking effects through it isn’t exactly easy or consistent.

[Nekojinn]

Enflamed does enough damage to be used on a twin-dance on-hit build IMO.

Envenomed applying 5 would be better, yeah. 

But I honestly just think that the best buff atm is just making it so they don't give altered tag, since they're both damage enchantments but... in most cases losing 10-ish+ SWA will mean the enchant is kinda pointless?