I reinstalled the game (again) and identified the point when weapon crafting + mods starts locking up my game.
Loading a save prior to completing the Old Temple - was able to craft a weapon
Loading a save just after completing the Old Temple, but before fighting the dragon - weapon crafting locks up game
I didn't open up or access the Black Emporium (these are old saves, from a recent playthrough), so (unlike other posters reporting the weapon crafting difficulty) I did not purchase any schematics from the BE.
I did, however, complete the schematic gathering/Veil fire rune quest in the Old Temple, concurrent to running through the main quest there. (Those schematics are all weapons, FWIW.)
Tested this out with a very minimal mod load (Skyhold outfit and Inquisitor HUD portrait replacers), merged with what I believe is the most recent Mod Manager (0.51a?). And I used the weapon crafting station at Stone-Bear Hold. *still aggravated that there are no weapon/armour modification stations in the DLC map*
/useless 'contribution' and YMMV