Can you distinguish type of attack received? (3.5ed)

[SinsI]

Combat Rhythm option of Stormguard Warrior feat from Tome of Battle allows to spend a turn doing melee touch attacks that deal no damage in place of normal melee attacks against an opponent. In exchange, on next turn each your melee attack gains a +5 damage bonus against that opponent for each melee touch attack that hit.

The usefulness of that feat can become negative if that opponent responds by taking a double move action on next turn, getting out of your melee range.

The question is - how hard is it for the opponent to recognize the use of this feat?
Can you distinguish between melee attack and melee touch attack received?
Can you determine whether you received no damage due to your DR or due to attack itself dealing no damage?
Do you need to make a roll of knowledge (local)?

P.S. Also, can you use that option on, say, only the last of your iterative attacks (that would've missed anyway)?

[Thrice Dead Cat]

I think, intuitively, one would be able to differentiate between a touch attack and a non-touch attack. That said, it may not be RAW.

I'm uncertain in regards to the DR question.

While likely not confirming to the RAW, a knowledge check would not hurt if the PC has no idea what might be going on. Local, history, and martial lore are the first the checks that come to mind.

[holywhippet]

I'd think, when setting up this feat, it would be obvious you aren't making direct attacks but rather touching parts of your opponent with your weapon. With few exceptions (like a paladin's smite evil) you can't hit someone at full force and not do damage so it should be clear the attacker is doing something other than attacking.

As for recognizing the feat being used, well that is tricky. I can't think of anything in the rules which lets you try to identify a martial feat being used. For magic you can roll spellcraft, but I can't think of a martial equivalent. In theory you'd just recognize the feat being used. You could possibly call for an intelligence check to see if, in the heat of battle, the target is smart enough to work out what they are being set up for.

[Lightlawbliss]

From my experience with real life combat, It is often really hard to tell if your opponent was trying to just touch you with his blade or if he was trying to cut you. Not getting hurt doesn't make that any easier.

An enemy with (for the common man) strong defenses fighting multiple foes at once might have a hard time noticing an attack that did nothing to said enemy. I have had times sparing a single foe where one or the other took a good smack and nobody noticed until minutes latter, I can easily imagine not noticing somebody making contact but causing no damage.

[Flickerdart]

Don't forget - missing someone's AC doesn't mean you didn't hit them, it means you didn't hurt them. There is no functional difference between someone touching your armor with his weapon and someone hitting your armor with his weapon but failing to hurt the flesh underneath.

The strength of the impact doesn't help either - touch attack or not, the enemy is still swinging as hard as he can, otherwise he wouldn't be able to apply his full Strength modifier.

[holywhippet]

Maybe a sense motive check is what is called from then? Detecting that your opponent is up to something rather than just being incompetent.

[Mr.Kraken]

Maybe a sense motive check is what is called from then? Detecting that your opponent is up to something rather than just being incompetent.

Could work, but I think a strong case for this one is definetly Martial Lore.

[Troacctid]

Yeah, this should totally be a Martial Lore check. I mean come on, that's classic Iron Heart tactics right there.

[SinsI]

Yeah, this should totally be a Martial Lore check. I mean come on, that's classic Iron Heart tactics right there.

What would DC be?
What if that opponent saw somebody using that feat before?
What if one of his comrades have that feat?
What if the opponent himself have that feat?
What if the player (controlling the attacked character) knows about existence of that feat?

[Lightlawbliss]

What would DC be?
What if that opponent saw somebody using that feat before?
What if one of his comrades have that feat?
What if the opponent himself have that feat?
What if the player (controlling the attacked character) knows about existence of that feat?

I would likely make it a dc 20.
There is this thing called a circumstance bonus, that covers many circumstances.
The last question depends on DM style

[Troacctid]

What would DC be?
What if that opponent saw somebody using that feat before?
What if one of his comrades have that feat?
What if the opponent himself have that feat?
What if the player (controlling the attacked character) knows about existence of that feat?

The DC to identify a maneuver is 10 + maneuver level. Since Stormguard Warrior is typically gained at level 6, I would give it a DC 13, same as a 3rd level maneuver. Fairly easy check, but it's trained-only, so you do need at least a little knowledge to get it.