This is the deal, the 'ability' Moon Glaive IS just a dummy skill, it does absolutely nothing. It's the "Upgrade" you research which does something...
The upgrade adds a bonus to maximum targets allowed.
@ SiorTapas: There is no direct way of doing this in-game, but in the Object Editor, just make the Weapon Type - Missil (Bounce) and change Maximum Number Of Target - 2 (Or more, of course ) and that should do it
If (All Conditions are True) then do (Then Actions) else do (Else Actions)
If - Conditions
(Item-type of (Item being manipulated)) Equal to MoonGlaive
Then - Actions
If (All Conditions are True) then do (Then Actions) else do (Else Actions)
If - Conditions
(Level of Moon Glaive for (Triggering unit)) Equal to 0
Then - Actions
Unit - Add Moon Glaive to (Triggering unit)
Unit - Order (Triggering unit) to research Upgrade Moon Glaive
Else - Actions
If (All Conditions are True) then do (Then Actions) else do (Else Actions)
If - Conditions
(Level of Moon Glaive for (Triggering unit)) Equal to 10
Then - Actions
Player - Set (Owner of (Triggering unit)) Current lumber to (((Owner of (Triggering unit)) Current lumber) + 1)
Else - Actions
Unit - Increase level of Moon Glaive for (Triggering unit)
Unit - Order (Triggering unit) to research Upgrade Moon Glaive
Else - Actions
Do nothing