Not a new player, still appropriate place to ask I think?
I noticed for High Allagan gear that has Determination, the Nexus can get higher secondary stats: the High Allagan Spear has 32 Crit/32 Determination, but Nexus can go 46 Crit/32 Determination. Same with High Allagan Bow and High Allagan Shield, which lose out to an identically statted Nexus as the latter can go beyond what the High Allagan has.

Is there a reason the Nexus is blatantly better in those cases?