There is a random event that increases the number of accessories from 3 to 4... but that is already the case.
<QuestDef InternalName="RandomEvent_ChangedWorld">
<DisplayName>The world has changed...</DisplayName>
<Description> My Lord, thanks to the progress of technology, units across the world can now equip 4 accessories instead of 3! </Description>
<AllowQuestRejection>0</AllowQuestRejection>
<FullscreenMovie>Movies\Minicut_Event_TheRevelry.bik</FullscreenMovie>
<QuestClass>Minor</QuestClass>
<Repeatable>0</Repeatable>
<TriggerType>TurnNumber</TriggerType>
<TriggerData>50</TriggerData>
<TriggerChance>10</TriggerChance>
<PostTriggerChance>10</PostTriggerChance>
<Treasure>
<GameModifier>
<ModType>Map</ModType>
<Attribute>ChangeWorld</Attribute>
<StrVal>0</StrVal>
<StrVal2>4</StrVal2>
</GameModifier>
</Treasure>
<QuestObjectiveDef>
<ObjectiveID>0</ObjectiveID>
<QuestEnd>1</QuestEnd>
</QuestObjectiveDef>
</QuestDef>
Maybe change it from 4 to 5. Like this
<QuestDef InternalName="RandomEvent_ChangedWorld">
<DisplayName>The world has changed...</DisplayName>
<Description> My Lord, thanks to the progress of technology, units across the world can now equip 5 accessories instead of 4! </Description>
<AllowQuestRejection>0</AllowQuestRejection>
<FullscreenMovie>Movies\Minicut_Event_TheRevelry.bik</FullscreenMovie>
<QuestClass>Minor</QuestClass>
<Repeatable>0</Repeatable>
<TriggerType>TurnNumber</TriggerType>
<TriggerData>50</TriggerData>
<TriggerChance>10</TriggerChance>
<PostTriggerChance>10</PostTriggerChance>
<Treasure>
<GameModifier>
<ModType>Map</ModType>
<Attribute>ChangeWorld</Attribute>
<StrVal>0</StrVal>
<StrVal2>5</StrVal2>
</GameModifier>
</Treasure>
<QuestObjectiveDef>
<ObjectiveID>0</ObjectiveID>
<QuestEnd>1</QuestEnd>
</QuestObjectiveDef>
</QuestDef>
