What do you get the pack-rat who has everything? A Pavise.
It is a very large shield used to protect bowmen; often during sieges. To me it looks more like a portable wall than a shield, but hey it obviously worked. Carrying your own cover is probably considered strange in regular rpg circles, and I’m not even sure what the stats for something like this would be in any game system. Parry, er no – its not moving. Cover from missile weapons? For sure.
In terms of size and load, they ranged from the size of other half height shields, which you would need to crouch to use, right up to full height barriers (basically doors). The real difference between a normal shield and a pavise seems to be the purpose built mount which allows the device to stand along without the user’s support, and be moved around slowly.
There are also a number of illustrations which indicate that they serve a number of other purposes, like having larger versions which infantry can also hide behind, or ultra-delux versions which small grates and doors built in to allow extra sniping options, and protection. It’s tempting to rework Leomund’s Tiny Hut into a Pavise effect.
Judging by the material easily found online they look to be taken to large battles and often decorated with ornate scenes. A basic pavise would be a section of wooden wall with a small foot stand (yup a wall). I could also see more advanced versions supporting a nice lazy curve, a shelf, perhaps a spine of some stronger material, and optional ways to get it around, like attaching wheels or lift bars. Heck add a few more splints of wood and the archery company is also carrying the dead around on readily available boards. Or just put a few bottles of booze on the inside and you’ve got a portable bar.
For stats, I’d say it should rule as cover as that is the clear purpose. If some archer is mad enough to pick the thing up and use it as a shield then make it like an ungainly tower shield – yes it gives cover but you’re not meant to pick it up as a proper shield. So +4 against other archers, and +0 against a swordsman who knows where to put the pointy end.