Lately, I've come across an increasingly large amount of information about Polish arms and armor during the 13th Century. Now, to be precise, I'm not simply referring to the equipment of the knights of Silesia, but more so to the seemingly much-avoided and understudied equipment from the more Eastern areas of the Piast Dynasty.
I've come across a lot of reconstructions of cavalry and the like from scouring forums both in English and Polish, and I've commonly seen them with shields we'd mostly refer to as pavises. Lithuanians of the 1200s are also depicted with them in modern drawings. Now, until today, I thought that they were simply an anomaly relegated to Lithuania and later century crossbowmen. However, my recent searches demonstrate that they were anything but an anomaly, even to the point where they were universally used in Mazovia.
For instance, let's take a look at a seal depiciting Trojden I of Mazovia:
Here, he is shown to have a four-sided shield with some sort of a line running down the middle.
A drawing of the same seal:
Another instance of its depiction in Mazovia, with the seal of Ziemowit II:
When one continues to search for the seals of rulers of Mazovia, similar-shaped shields just keep popping up.
Even with this guy, Waclaw of Plock, who seems to be wearing a surcoat and maille, is shown holding a "pavise" type shield and even wearing a brimmed helm:
Now, to be honest, I do not think that those shields were referred to as pavises by the Poles. In fact, as far as I know, there is no documentation of what they were referred to historically. The modern Polish article that I was reading that described them refers to them as "Pawęż", but that is also likely not a regional term.
The reason for this shield being so apparently prevalent in Mazovia? The Duchy of Mazovia bordered the Duchy of Lithuania, and this is likely an example of a mixing of east and west. I think that a lot more archaeological and artistic research should be put into this matter, and not just by those who live in Poland.