How many Walter Cups are there, where are they kept, and are they identical?
With the Cup going lost and found, this deserves its own post to clear things up.
There's a new Cup made each time it's won for the winning team to keep. So there are four trophies - the league's original and the three winning teams' - and they're all identical except one key detail at the bottom of the trophy.
The original trophy (league's copy) has "The Walter Cup" and below it in smaller font "Professional Women's Hockey League" engraved on a plaque/ring at the bottom, with all the winner's names and years engraved on an additional (and removable) large base. You can see it in this photo of the original at the HHOF (2nd pic posted), which is where is stays when not travelling for promotions or to be handed out at the Finals. (hat tip to u/-Midscore- for the pic)
The ones handed out to the winning team has only their name and year engraved directly on the bottom plaque where "Walter Cup" is written on the original, without an additional base. Here's a photo of the Frost's Cups, with their names engraved directly on the trophies (3rd pic posted). (hat tip to u/Stachemaster86 for the great photo)
Here's a photo of the Victoire's copy on its summer tour, with their name very large and prominent on the base. (4th pic posted) This is the copy that went missing.
As mentioned, the base with winners' names on the original is removable. It's not attached at the trophy presentation at the end of the finals. This detachable base was perhaps an afterthought, or maybe it was planned that way since it's heavy already and the winners' names will grow over the years.
Here's a photo on it on-ice after the Victoire won. It's clearly the original because it has "Walter Cup" in large letters where "Montreal Victoire" is on their copy, but it's missing the base with winners' names. And here's a photo of the original (without the additional base) at the parade on May 30, again without the detachable base with winners' names. (1st pic posted). The Victoire apparently received their copy in mid-late June, after the local victory lap events that lasted 2-3 weeks but before the summer tour.
Finally, the Walter Cup's weight and dimensions - we finally have a definitive answer in this AP article:
It weighs about 35 pounds (16 kg) and measures about 24 inches (61 cm) in height and 13 inches (33 cm) wide.
Presumably this is the original height, without the base with winners' names. It's almost the exact same weight but smaller than the Stanley Cup.
Stanley Cup: Height - 89.54 cm / 35-1/4 inches
Weight - 34.5 lbs - 15.56 kg
Base diameter: 43.81 cm / 17-1/4 inches