Unknown Strong Will cause

[Rodmar18]

This Draconian Dreadnought and her stack's troops apparently have "Strong Will", and I don't know why.
Would anyone have any idea?

The Engineer was just berserked by enemy warlord, and I figured that I could dispel the status with Break Charm.

- Hovering over the hero, adjacent engineer, and adjacent hunter display the same "Strong Will 1 turn".
- Other units are further away and don't display the effect when hovered over (or are said to be too far away).
- No Strong Will ability is listed on their unit panels.
- The hero has Imperial Authority, and no other ability I could figure related to any Strong Will buff.
- Leader (not present) is an Archdruid, and both are level 8-9.

 

[Ericridge]

An visit site?

 

[Hiliadan]

Break Control gives Strong Will for 1 turn.

 

[Rodmar18]

You are right. At the time, I thought that Break Control would list the effects it could dispel (here, only one effect: Berserk). But no; neither it nor Dispel Enchantment do list the effects they dispel, and they only tell their number.