when switching form any normal item to one with attributes, when switching and a very brief moment later hiting something, the attributes of the item switched to are not applied, although the enchantments are applied. (As a side note this can be tricky to pull of and I've only tested with the attack damage attribute since the otherones are not responsible for damage) If someone would like to test this to further confirm this bug I'll leave the command for the sword i used underneath my post.

(requires commandblocks /give @p minecraft:command_block)

/give @p minecraft:diamond_sword 1 0 {AttributeModifiers:[{AttributeName:"generic.attackDamage",Name:"generic.attackDamage",Amount:9999,Operation:0,UUIDLeast:307806,UUIDMost:856305,Slot:"mainhand"},{AttributeName:"generic.attackSpeed",Name:"generic.attackSpeed",Amount:1024,Operation:0,UUIDLeast:307800,UUIDMost:856300,Slot:"mainhand"}],ench:[{id:20,lvl:1}]}