You can create a guard villager with a sword in your off hand, however the guard villager equips a duplicate of what is in your main hand.
Occurring/Tested on version: 1.2.6 in the Enigmatica 6 Expert Pack.

Replication Steps:

1. Equip a useless sword in off hand
2. Hold item you wish to duplicate in main hand
3. shift right click villager
4. Kill villager

Expected Results:
Villager drops the sword used to create the villager
Actual Results:
Villager drops the items you had in main hand effectively duplicating them.