Boost Atma Weapon

Code:

C2/0E58: A9 05 00     LDA #$0005
C2/0E5B: 20 D1 0D     JSR $0DD1      (Divide 24-bit Damage in $E8 by 64. [note that
                                     calculation operates on 4 bytes])

According to Assassin's disassembly, entering that subroutine at $0DD1 takes the number and divides it by 2^(A+1).
Because A is set to 5 right before the subroutine, the result is 2^6, or division by 64.

You could change LDA #$0005 to #$0004 to make the division 32 instead (doubling the damage), but getting a divisor that isn't a power of two won't be possible with an in-line change.