Well this is an interesting question. I can say that in all my years of playing I personally have never encountered one, however that does not mean it has not been invented. I will need to check with the games creator Scott Jones for definite answers on this question.

This question prompted me to do some research into the rules for inventions which I recalled seeing in one of our earlier versions of the core rule books and I found some very interesting information which I will share with you. Please understand that the following information has yet to be released and may change considerably once we edit it for release in the up and coming World Guide. It was previously found within the pages of the very first draft of the World Guide which we are currently expanding and reading for the public.
The process for inventing something new is as follows. Not to tease you mercilessly but before I release this information even here upon our own forum I must get permission from the games creator Scott Jones and Andrew Bowman to make absolutely sure this is something which can be given out early. Stay tuned and I will update you on my progress.
The rules for invention can cover nearly anything the Game Master wishes to allow to be created within the scope of his game and gives players who wish to play inventors a way to impact the world in a substantial way.
See you soon with the answers.

Griffin, you are totally free to share the "Rules for Invention" which we intend to include in the Appendices of the World Guide. In fact, to make it easier for everyone, I'll provide a link below to open up a document I've added to another area on the forums that include just what you're looking to share! dardunah.com/forum4/index.php/…entions-and-Skyships-pdf/

The concept of a petard is certainly not a new one, and its essential form in the world of Shard could look like what you see in the shared image above, or it could exist in an even simpler form as a grenade or cask of explosive powder shored up against a door so that most of its explosive force is directed at the door itself... In the shard rules we discuss the general idea of "siege weapons", and this would certainly qualify as a siege weapon just as assuredly as a large battering ram... And, of course, we have rules in the Basic Compendium to cover explosives and explosion damage of all kinds...

This device is, essentially, a short, fat "cannon" meant to blow a door or portcullis open...and we certainly have cannon in Dárdünah. As such, though we haven't specifically described petards as being a part of the setting of the Shard RPG, there's no reason why a GM couldn't use a petard as part of a description of a type of device used in a siege, or as part of some plan to breach the main gate of some palace or what-not... Likewise, if a GM wanted to allow their players to "introduce" the idea of a petard into their campaign as if it had never existed before, it could certainly be something their players could "invent", using something like the "Rules for Invention" which we'll eventually release officially with the next book...

Hopefully this helps!

Enjoy!

Scottie