I want to make a character build like that of Hyakkimaru from the show Dororo, but when determining aspects like his body, I am in need of some tips. The character is missing his arms and replaced them with swords that are covered by prosthetics. The issue is whether to determine his attacks as normal unarmed strikes or as melee weapons and in general how to handle his damage output. 

Edit: Thank you all for the help, I appreciate it! Now I can complete my character build. 

Natural weapons, 1d6 Dex

Quote from IamSposta >>

Natural weapons, 1d6 Dex

 
Str for melee.

Quote from Cyb3rM1nd >>

Quote from IamSposta >>

Natural weapons, 1d6 Dex

 
Str for melee.

 I was thinking finesse because I picked Shortsword/Scimitar stats.

Yeah, it makes sense to me to treat them as finesse weapons... give the player a few options. I think it does make sense to class them as "natural weapons" instead of "unarmed strikes", mostly for the sake of spells and abilities that differentiate between the two. 

The reason why some weapons are finesse is because they're light and small. An entire arm of metal and prosphetics would not be light or small.

There's a reason why Tabaxi claw attacks are strength despite being a creature that all about agility.

A dagger is often about 12 inches of light metal on a small handle. A shortsword is shorter than an average forearm, typically about a foot or 16-18 inches of metal as opposed to longswords that are more than double that [upwards of 40 inches] (it's used for indoor spaces and narrow halls because a longsword could not be used properly in such places due to the size - a shortsword is basically a slightly longer dagger, some are slightly curved like a wakizashi). A scimitar is an odd duck because in real life it wouldn't be finesse as they've got too much metal and are only a little shorter than longswords, just highly curved. It's finesse because the developers don't actually understand these weapons enough and wanted more finesse options so 'meh'd' it. But, with an average length of over 30 it's much closer to being a longsword type (and often confused with some types of sabres) and has too much metal and weight to actually be finesse.

So unless the sword arm is like half the length of a normal arm - it's going to be too big to be "finesse".

My forearm and hand (elbow to fingertips) is roughly the length of a Shortsword.

Does the character have elbows?  If he has them, I would allow Dex.  No elbows means strength only.

I was basing things on "full arms" but I looked at images for the character the OP mentions and indeed the blades are only below the elbow, making them more alike shortswords.

In this case, I would agree the stats should be based on shortsword and finesse. 

Consensus!

How does he eat? 

Well the first post mentions that he has prosthetics worn over the swords... no idea how dexterous they are, but at the very least they can probably be designed to hold a spoon.

that makes sense, thanks! 

Quote from JayDan >>

How does he eat? 

 He cuts up his food into smaller bites.

Quote from Mattwilljackson >>

Quote from JayDan >>

How does he eat? 

 He cuts up his food into smaller bites.

 😂🤣😂🤣

Forget about food.  What about  bateing the master, (scratch that, reverse it)

OUCH

Quote from Mog_Dracov >>

Forget about food.  What about  bateing the master, (scratch that, reverse it)

OUCH

 He’s so cool he doesn’t have to.