GetWeaponDrawn returns 1 before weapon is attached
TestWeaponDrawn.ESP "Startscript TestWeaponDrawn" on any NPC to test.
In vanilla, GetWeaponDrawn starts to return 1 after 32 frames after combat starts: probably the time before the weapon is attached in the drawing animation. In openMW, GetWeaponDrawn starts to return 1 after 2 frames after combat starts.
For GetSpellReadied, there is no delay and both vanilla and openMW already behave the same way.
GetWeaponDrawn also stops returning 1 while weapons are switched, probably for the same reason, attach and unattach in the animation. TestWeaponSwitch.ESP "Startscript TestWeaponSwitch" on any NPC to test.