Tested BG2EE /v1.2.2030 (and can be applied to BG1EE v1.2).
Well.. much easier to explain than http://forum.baldursgate.com/discussion/26146/bug-bard-blades-defensive-spins-free-action-potion-spell-ring?new=1
. Easier to observe too..Observed behaviour:
1. You use your FA potion/spell/item(equiped) FIRST.. you launch your Speed boost (potion/spell)... you loose/waste
your Speed Boost (potion/spell)... (no speed effects added, FA prioritory, only FA icon on portrait - SP bypassed by FA effect first : ok).
2. You launch your Speed boost (potion/spell) FIRST.. you launch FA potion/spell/item(equiped)... eveything is working perfectly together.. (FA+SP icons on portrait ok) ...Expected behaviour:
Well.. seems obvious.. 2. is not right/logical if 1. is considered 'normal' (or the reverse)... one or the other..
Easy exemple to get it :
Keldorn armor with Free Action (FA).
1. You let Keldorn armor on him, launch a spell haste(group)/imp.haste(he only) or make him drink a speed potion : potion/spells are waisted. (similar to http://forum.baldursgate.com/discussion/26146/bug-bard-blades-defensive-spins-free-action-potion-spell-ring?new=1
2. You remove Keldorn armor FIRST.. launch a spell haste/imp.haste or make him drink a speed potion .. put back his armor.. you got both effects, SP+FA ok.. (same with the FA ring of course).
..of course, in combat, you can't remove armors (case 1.)..so you will loose everytime SP (if you had forgotten that) .. ^