There are 4 different types of hand upgrades in Devil Daggers V3.1. You unlock these upgrades by collecting gems. Each upgrades makes the player significantly more powerful.

Name
Level 1
Unlocks at
N/A
Default spray
20 daggers per second
Default shot
10 daggers per shot
Homing spray
N/A
Homing shot
N/A
Name
Level 2
Unlocks at
10 gems
Default spray
40 daggers per second
Default shot
20 daggers per shot
Homing spray
N/A
Homing shot
N/A
Name
Level 3
Unlocks at
70 gems
Default spray
80 daggers per second
Default shot
40 daggers per shot
Homing spray
40 daggers per second
Homing shot
20 daggers per shot
Name
Level 4
Unlocks at
150 stored homing daggers
Default spray
106.67 daggers per second
Default shot
60 daggers per shot
Homing spray
40 daggers per second
Homing shot
30 daggers per shot