Another aspect which can show how
Anti-Tank Gun
Attack 1
Defense 3
Move 1
Cost 4,
+1 Def to 1 Inf
is still balance:
1 Infantry (A1-2 D2-3) + 1 Artillery = A2 D2 + A2 D2 = A4 D4, 2 hits for 7 IPCs.
1 Infantry (A1-2 D2-3)+ 1 Anti-Tank Gun = A1 D3 + A1 D3 = A2 D6, 2 hits for 7 IPCs.
The same overall number are kept, 8 combat points, same hits, same cost.