Balan, Wandering Knight has double strike as long as two or more Equipment are attached to it.
: Attach all Equipment you control to Balan.
8/25/2017 Balan’s activated ability has no timing restriction. You can activate it any time you have priority.
8/25/2017 If Balan deals first-strike damage and then gains double strike (most likely because it picked up some Equipment with its activated ability after first-strike damage was dealt), it will also deal regular combat damage.