Hey there LoganX. Congrats to your son on getting to level 34! So you are asking about if your son is at a disadvantage due to light level in the Crucible correct? If he is playing in normal Crucible matches with the description of the mode as “Level advantages disabled”, then your son does [b]not[/b] need to be a specific light level to compete with others. Your son can use any weapon and gear his heart desires in normal Crucible games be it a common white engram weapon or even a blue & green engram weapon (and yes, legendary gear/weapons and exotic gear/weapons). The reason for this is because all weapons don't check light attack/defense values in those games with no Level advantage, making it so that even newer players with non legendary and/or exotic gear can have fun in the Crucible. Light advantages are normally only turned on for special PvP events like Trials of Osiris and Iron Banner where Guardians need to use their best gear to gain an upper hand against their competition. Hopefully I answered your question well enough.

If you mean your son isn't able to do enough damage, then you are right. Level advantages are disabled, but bungie put severe damage falloff on all weapons except scout rifles. Plus, your armor now counts more than ever. Armor reduces damage level even more.