What are the consequences of equipping a cursed weapon in barony?
Is there any stat decreases or is it just that you can't switch weapons until it is broken?
According to https://baronygame.fandom.com/wiki/Item_Info , an item's blessings and curses "Determine the power of its stats". I interpret this to mean that it affects the weapon's stats by adding the bless/curse modifier. For example: 
A quarterstaff has +5 attack, so a -2 Quarterterstaff would have (+5 -2 =) +3 attack instead, and a -1 Bronze Sheild, with a base AC of +2, would have an AC of +1.