Use of the Cestus in D&D

[Scorppayne]

So I just wanted to be clear on a few things, the game I'm referring to is my first, though I've familiarized myself with the rules, and we're about 10 sessions in at this point.

My character's a barbarian, and I started off with a normal sword, and a cestus on each hand, which was fine with my DM completely. Though if I try to use them outside of punching with some extra damage, its not really allowed. For example, just recently he introduced sword-breakers into the campaign, which, as a reaction, allows a user to have the possibility of succeeding in a saving throw, disarming their opponent. I feel like cestus should have an option to parry as a reaction, if this is the case, considering it's the same principle, and its not like it would be an automatic thing, I'd still have to succeed on some roll. He also said the metal-laced gloves didn't technically count as shields, so I wouldn't get an AC bonus, which is understandable. I know the DM gets final say, but I try to make the most of my arsenal, and I just need to know if I'm missing something here.

Also, on the wiki, the cestus is labeled as having the 'special' property, but I couldn't find specifically what it does in this case. Help is appreciated!

[Sicarius Victis]

Would you be willing/able to post a link to the website you were using, or at least tell us the specific name of it?

Also, it shouldn't have a parry ability. At the very least, none more than any other weapon.

[Scorppayne]

Would you be willing/able to post a link to the website you were using, or at least tell us the specific name of it?

Also, it shouldn't have a parry ability. At the very least, none more than any other weapon.

dandwiki.com/wiki/Cestus_(5e_Equipment)

I do realize that this is a wiki for homebrew essentially, but I couldn't find it in the actual handbook, so I'm assuming this is what my DM would be using for reference

[Zaydos]

It's homebrew (it says so on that page). The special is probably the stuff on that page. As for the parry ability there's no reason for it to have the ability over a dagger, shortsword, or any other off-hand weapon, and actually parrying daggers (which are between D&D dagger and shortsword) and full-fledged gauntlets both were better for it (cestuses were used that way... in the bronze age before the existence of the other two).

[Mellack]

No way cestus should get to parry. They are less than even gauntlets, which do not allow it. You are already being lucky in that your DM seems to be letting you wield a sword in the same hand you have cestus on. They could have easily said that it interfers with the proper handeling of a sword.

[CaptainSarathai]

Unless you're thinking of something different, cestii are just boxer-wraps, maybe with some metal plates, rivets, or spikes added in.
On the bright-side, unless you're using something with a shell guard or d-guard, or a weapon with a strangely finessed grip (like a katana or bow) then cestii shouldn't be a problem for grasping a weapon effectively.

On the downside, they're not any better than brass-knuckles in terms of transmitting damage, and not any better than leather gauntlets at deflecting blows.
I wouldn't give them a parry. I wouldn't really make them any better than an unarmed strike. In fact, I'd make cestii a D4 weapon with Light. If they have "tiger claws" instead of just spikes or rivets, I'd consider making them Finesse weapons.
This way, they deal lethal damage, can be targeted by spells and so forth as if they were weapons, can be magical, and so on.