Dire Encumbrance is a measure of Encumbrance that impedes the activity of a character. Most Shields/Weapons are leveraged as part of the ENCumbrance system; Medium Armor Familiarity/Proficiency offsetting much is it is due to Armors.
Condition: Load/Encumbrance > 2x Encumbrance Capacity (EC)
EC = Size Factor + Strength mod; Some Features adjust ENCumbrance.
* = Movement adjustments includes penalty from Exhaustion unless zero, but not Difficult Terrain.