By hitting item level Breakpoints, which are hidden stats that can be reached with your weapon and armor, you can increase the statistic tier of your weapons and armor. A universal layer of tiers can be upgraded at any Blacksmith in Diablo 4 that buffs all stats massively based on your level. The next level Breakpoint tier is 340, so an armor piece upgraded at 331 will gain much more power than 10 if I upgrade it with 300 power. All stats will be boosted as you move up the tiers.
Related: Diablo 4: The Best Nightmare Dungeon Tiers for Experience XP
All Item Power Breakpoint Levels in Diablo 4 Listed:
Level 1: Power 1 – 149
Level 2: Power 150 – 339
Level 3: Power 340 – 459
Level 4: Power 460 – 624
Level 5: Power 625 – 724
Level 6: Power 725+
Related: Secrets of the Dismount Ability in Diablo 4
At a highest item power weapon of 711, and at level 59 in the game, you can reach the final Breakpoint tier by the end of the Nightmare difficulty. The important aspect of this hidden stat, however, is knowing when to upgrade it. If it means passing the Breakpoint tier, it might be worth spending a few extra resources.