You can edit the properties of any object that derives from the Actor class using the editactor console command:
Also worth noting that if you pass trace as a param then this will display the properties of the object you are aiming directly at
As mentioned in the Gameplay Debugging page, this is ideal for something like fine tuning a vehicle but I guess you could go as far as tuning the lighting or pickup placements.
There are a few other commands available such as EditObject:
editobjectconsole command makes the properties of a specific object in the game available in the property window
editdefaultconsole command makes the properties of a class default object available, similar to specifying a class with the
editdefault UTProj_LinkPlasma editdefault class=UTProj_LinkPlasma
TheThere's lot of other information in there too from data inspection to code profiling, as always the docs are there you've just got to know what you are looking for at the time.
editarchetypeconsole command makes the properties of an archetype available. The archetype to edit is specified by passing the path (Package.Group.Name) to the archetype following the command. Like the
editdefaultcommand, this command is also extremely useful for archetypes that are used as templates for objects that are frequently spawned, such as projectiles or units in a real-time strategy game, or for archetypes used as data definitions or content holders.