Equipment value depends on the hero, army and job you expect it to perform. Start by identifying one reliable attack composition, then invest in the equipment used by that composition before spreading ore across every unlocked item.
Prioritize complete combinations
A working two-item combination on each deployed hero is usually more useful than one highly upgraded item surrounded by neglected partners. Consider activation timing, survivability and whether the effect supports the main army.
Recheck after balance updates
Equipment balance can change. Record the guide review date, read official update notes and avoid treating any ranking as permanent.