You may have noticed that you get higher-level weapon drops as you continue to increase your Descendant level in The First Descendant. We'll tell you everything you need to know about weapon level caps.
How to Upgrade Your Weapons in The First Descendant
The max weapon level in The First Descendant is probably 100 (possibly even higher). Unfortunately, we can't give you a concrete answer, because no one has gotten such a high weapon.
One thing we can say for sure is that contrary to popular belief, weapon levels do not stop at 40, like Descendant levels do. Many players have reported that they have maxed out their Descendant (or several) and started doing end-game activities, but they continue to receive weapon drops that are much higher than their Descendant level.
While the maximum weapon level during the closed beta was 36, things have been ramped up considerably for the full release.