As far as I know there is no beneficial treatment for Vietnamese handbags, wallets, etc.
What products are you looknig to import and what material is used in the construction of the products? If these are leather bags the duty rate is not 15% - 25%.
If the goods are made of leather the following classifications apply:
Handbags valued not over $ 20.00 each - 4202.21.6000 at 10% duty
Hangbags valued over $ 20.00 each - 4202.21.9000 at 9% duty
Wallets, passport holders, similar small goods - 4202.31.6000 at 8% duty
Travel, sport (duffel) and similar bags - 4202.91.9030 at 4.5% duty.
These are the normal rates for these items if they are made of leather. There is no special treatment for a Form "B".