Almost everything can be maxed during a first run with enough grinding, but certain upgrades need ng+. Unlock all base weapon skills through muspelheim trials and side quests, max atreus's bow skills naturally through story progression, and upgrade most armor sets through endgame content like berserker fights. For weapons, focus xp farming on leviathan axe and blades first, since draupnir spear unlocks later around chapter 10

Some late-game items and peak upgrades are locked behind ng+ though, just so you know. The special spartan and zeus sets need those gilded coins you only get in ng+, and reaching level 10+ gear needs materials from the second playthrough. Good news is you can get about 95% done in 60-70 hours if you're thorough, hitting all the trials and post-game content. Tip: save some hacksilver and dragon claws since they get scarce near the end

Ng+ opens up those fancy valhalla enchantments at the blacksmith, lets you convert gear to plus versions, and throws tougher enemies at you for skill mastery. The cursed and blessed equipment upgrades need those special ng+ resources too, so don't stress if you can't max absolutely everything first time around