Striking refers to the Ring of the Striking, a 
Trinket in 
Blox Fruits. The source page is a simple stub: it only indicates that this ring is part of the Trinkets, without detailing its effects.
What We Know
The only official information available consists of a single sentence: "The ring of the Striking is a Trinket". For the general functioning of this type of object, see the Trinkets page.
Red Army
Rip Family
Safe Zone
Sea Danger Level
Sea Exploration Group
Server Browser
Settings
Shop
Skins
Slayer Skin
Stats
Striking
Stun
Subclasses
Summer Chest
Summon Sea Beast
Sunken Chest
Swords
Teleportation
Titles
Trading
Transformation
Trees