I've tried to edit the .ini file but it keeps wanting to default to low resolutions. How can I get this to do something like 1920 X 1080?

Try adding Width=1920 Height=1080 to the launch options
Be aware that your hud will be small as it doesn't scale

Further information found here
https://www.wsgf.org/dr/dungeon-siege-ii

Perfect. I only changed the .ini for base DS2 and didn't even think there'd be a separate folder for Broken World as well. Changing that fixed it (though I imagine there is no way to fix the main menu, is there)?
Thanks!

Glad you where able to get it sorted out.
Sorry no way to change the main menu, both DS1 and DS2 use prerendered menus that are stuck at the resolution and 4:3 ratio

In DS! the bundled wrapper lets you to select the output resolution of the game priorizing over the internal resolution. The menu in DSI at retail was lower than 1024x768. But if the wrapper is configured at desktop resolution even the menu will be scaled up. Aspect corrected to 4:3.

DSII does not use any wrapper apparently, and the menu was lower than 1024x768 as well. Normally You will have different menu resolution and game resolutions.

But if you have installed the Broken World expansions I remember that the menu layout was changed in design and its resolution was higher than the vanilla one.

Greetings