Not sure which mod added it, but something added an effect to the sword that applies a "set proficiency" with type "Gun" ... That seems suspicious. That effect isn't on the version from Item Revisions.
Can you check if it still crashes if you copy the SW2H16.ITM from IILEARNTHROUGHUSE\backup\2001 into your override folder?
Partial analysis of the changes made:
Mods affecting SW2H16.ITM:
00000: ~BP/SETUP-BP.TP2~ 0 0 // Big Picture, core component (required for most subcomponents): v181-b4611
BWP Fix
// didn't check yet
00001: ~SETUP-REVISEDBATTLES.TP2~ 0 0 // Improved Battles - "erebusant's Patching Version" v6: v6.3
BWP Fix
// applies a "relabel" macro to all weapons .. probably OK
00002: ~SETUP-SPSTUFF.TP2~ 0 6 // Arcane Fist, by Drizzt1180: v10
// applies a tweak to "usable by" settings for all items ... probably OK
00003: ~ITEM_REV/ITEM_REV.TP2~ 0 17 // Weapon Changes: V3 Beta 1.16
// changes the melee effect of the sword to cast DVVAMPIR.SPL (which is also provided by item revisions) ... probably OK ?
00004: ~ITEM_REV/ITEM_REV.TP2~ 0 1080 // Enchantment Doesn't Affect Speed Factor of Weapons: V3 Beta 1.16
00005: ~ITEM_REV/ITEM_REV.TP2~ 0 20 // Backstabbing Penalties for Inappropriate Weapons -> All Melee and Ranged Weapons Usable For Backstabbing: V3 Beta 1.16
// didn't check yet
00006: ~ATWEAKS/SETUP-ATWEAKS.TP2~ 0 152 //
PnP Fiends -> Mod-added fiends are also affected: v4.50b1
// applies a "relabel" macro to all weapons .. probably OK
00007: ~IILEARNTHROUGHUSE/SETUP-IILEARNTHROUGHUSE.TP2~ 0 2001 // Learn Through Use
// didn't check yet
00008: ~SETUP-LOLFIXER.TP2~ 0 11 // Item Stuff - Duplicate Item Effect Remover: 10122015
// didn't check yet
00009: /* acted upon in an indetectable manner */~GENERALIZED_BIFFING/GENERALIZED_BIFFING.TP2~ 0 0 // Generalized Biffing: v2.2
BWP Fix
00010: /* acted upon in an indetectable manner */~GENERALIZED_BIFFING/GENERALIZED_BIFFING.TP2~ 0 0 // Generalized Biffing: v2.2
BWP Fix