I went through Dangerous Covenants a few days ago and found the wrist mount for Ranged(Light) and the Vamblade, but no option for other light melee weapons.

Deconstructing the Vamblade I came up with:

Armed Vambrace

Description:

Initially designed to allow species with poor grip strength or no opposable thumbs to use light melee weapons, the Armed Vambrace mounts a light melee weapon (Encumbrance 2) on an armored forearm guard.

Requirements:

1 handed melee weapon Encumbrance 2 or less.

Base Modifiers:

Innate Talent: Quick Draw

Weapon Type: Brawl Mod – change combat skill from Melee to Brawl

Modification Options:

1 - Defensive +1 Mod

Hard Points: 0

Encumberance: 2

Rarity: 4

Cost: 300

Using this attachment with a combat knife to build a Vamblade:

Combat Knife: 25 cr +1 damage

Attachment: 300 cr

Innate Talent: Quick Draw (equates to "allowing the user to retract or extend the blade with a simple flick of his wrist")

Brawling skill instead of Melee

Mod: 100 cr - +1 defensive

Encumbrance set to 2.

Rarity set to 4

Blurb:

Brawl, +1 damage, Crit 3, Enc 2, HP 0, 425 cr, Rarity 4, Quick Draw, +1 Defensive,

Since the vamblade actually adds 1 HP to the combat knife and has sunder & accurate 1 when paired, the slightly lower cost should be acceptable.

Alterations I'm considering -

1) Changing the Melee->Brawl mod to a Base Mod (Optional)

2) Changing the Melee->Brawl mod to an Optional Mod

3) Adding an Optional Mod to revert from Brawl back to Melee

4) Dropping the Max Enc from 2 to 1

Recommendations or things I've overlooked?

Why not just say a race has made a vibrosword or vamblade or whatever weapon, exclusive to their race's anatomy?

Looks solid, would definitely try at my table

Would add something like "can not be disarmed through critical injury or narrative action".

Looks solid, would definitely try at my table

Would add something like "can not be disarmed through critical injury or narrative action".

Cut off the arm (via a critical injury) and then explain again how the character is still using the weapon.

Beyond that, in this system, narrative action can pretty much override anything with the right explanation.

Yeah, just add an "except" there: "Cannot be disarmed, except through critical injury or narrative action."

Unless you mean the Sudden Jolt Critical Injury where the PC drops what he is holding.

So maybe, "Cannot be disarmed so long as the user's arms remain intact."