Attila - Units Upgrades in Multiplayer

Cost
Regardless of unit price, upgrades cost 15 per chevron.

Effect
The first chevron inceases melee attack and defense by +2, morale by +1.
The following chevrons incease melee attack, morale and defense by +1.
At level 5, two silver chevrons, a unit gets -1 to fatigue.
This increases further to a maximum of -3 fatigue, an effective reduction of 33% of the fatigue cost of running and 10% of the fatigue cost of fighting.

When to upgrade
Since upgrades are so cheap, it is well worth giving strong units a single chevron. Giving 10 units 1 chevron is well worth it in many cases - for example 6 melee cavalry and 4 melee infantry. For this you can only get the cheapest skirmishers or meatshield units. Preferences vary - sometimes you want the extra unit, sometimes you want more punch out of all your units.

A word of caution
Since weapon damage, health and armour remain unchanged, upgrade sturdy units with good weapons and health over cheap units with low health, armour and damage.