Well, In a way yes, there is a way to add more than 4 abilities, but as you said it is through triggers.
-Say, you make a Sniper Rifle Item..
Abilities: Critical Strike, Wind Walk, Evasion, +Damage modifier
-However, because its a Sniper rifle, WE NEED RANGE!
So...we make ourself a trigger..
Basically Its like this:
Code:
Aquire Sniper Rifle
Events
Unit - A unit Acquires an item
Conditions
(Item-type of (Item being manipulated)) Equal to Sniper Rifle
Actions
If (All Conditions are True) then do (Then Actions) else do (Else Actions)
If - Conditions
((Hero manipulating item) is an illusion) Not equal to True
Then - Actions
Unit - Add Sniper Ability to (Hero manipulating item)
Else - Actions
So if He picks up the item, he gets the ability. Now, what about it he drops it?
Code:
Drop Sniper Rifle
Events
Unit - A unit Loses an item
Conditions
(Item-type of (Item being manipulated)) Equal to Sniper Rifle
Actions
If (All Conditions are True) then do (Then Actions) else do (Else Actions)
If - Conditions
((Hero manipulating item) is an illusion) Not equal to True
Then - Actions
Unit - Remove Snipe Ability from (Hero manipulating item)
Else - Actions