The requirement for this trophy is:
Use 10 different melee weapons to defeat enemies
Note the word enemies. Triads are obviouly enemies. However, pedestrians also become enemies if and only if they start attacking you (I have only ever seen male pedestrains attacking me). If they do not attack you and you kill them with a melee weapon, that will not count towards the trophy requirement.
A list of melee weapons are as follows
- Baton ["Yau Ling Courts" Drug Bust ]
- Briefcase [from male pedestrians, Central]
- Cooking Wok [Food Vendor outside Aberdeen apartment]
- Crowbar ["Stickup and Delivery" story mission]
- Fish ["Club Bam Bam" story mission]
- Grocery Bag [Pedestrians]
- Shopping Bag [Pedestrians]
- Kitchen Knife [Triads]
- Knife [Triads]
- Lock Cutter [automatically acquired during story mission "Dockyard Heist"]
- Machete [automatically acquired after story mission "The Election"]
- Meat Cleaver ["The Wedding" story mission]
- Handbag [from female pedestrians]
- Purse [from female pedestrians]
- Tire Iron [obtainable from trunks in any vehicle]
- Umbrella [pedestrians, during rainy weather]
