Which civilizations have the Steel Bolts card?

Germans, Swedes, Maltese and Poles.

What does Steel Bolts do in AoE3?

Order Crossbowman: damage bonus against Heavy Infantry +0.75, range (Ranged) +2, range (Ranged (defend)) +2, range (Ranged (stagger)) +2. The game says: "Order Crossbowmen gain more range and inflict greater damage to Heavy Infantry and Buildings with their bolts."

Home City card

Steel Bolts

Steel Bolts (tech ID DEHCREVImprovedCrossbows) is a Home City card in AoE3: Definitive Edition 100.19.18309, in the decks of 4 civilizations, sent from the Industrial Age. Effect: Order Crossbowman: damage bonus against Heavy Infantry +0.75, range (Ranged) +2, range (Ranged (defend)) +2, range (Ranged (stagger)) +2.

Quick answers (3)

Which civilizations have the Steel Bolts card?: Germans, Swedes, Maltese and Poles.
What does Steel Bolts do in AoE3?: Order Crossbowman: damage bonus against Heavy Infantry +0.75, range (Ranged) +2, range (Ranged (defend)) +2, range (Ranged (stagger)) +2. The game says: "Order Crossbowmen gain more range and inflict greater damage to Heavy Infantry and Buildings with their bolts."
What is the tech ID of Steel Bolts?: DEHCREVImprovedCrossbows.

Order Crossbowmen gain more range and inflict greater damage to Heavy Infantry and Buildings with their bolts.

What it does

Order Crossbowman: damage bonus against Heavy Infantry +0.75, range (Ranged) +2, range (Ranged (defend)) +2, range (Ranged (stagger)) +2, line of sight +2

2 further effects (interface, visuals or AI) not listed.

Cost: 1
Sent from: IV
Times it can be sent: 1
Game ID: DEHCREVImprovedCrossbows

In these decks

Source: techtreey.xml and the Home City files, AoE3: DE 100.19.18309 (build 25040513).