Al said:
This is certainly an interesting line of argument, but it's very campaign-dependent. I favour humanoid classed opponents, so the new DR is less of an issue.
I'd argue that the assumed campaign setting probably has a significant number of monster-combats though. It's important to note, however, that even in a humanoid dependent setting, spells like Righteous Might (grants alignment DR), Protection from Arrows (DR/Magic), Summon Monster (Fiendish/Celestial templates grant DR/Magic), Stoneskin and Iron Body (DR/Adamantium) mean that the new DR system will have a significant effect.
Nevertheless, the point is solid. In most cases, I would argue that fighters are better off having a single 'primary' weapon and a few backups. However, in this case, the greatsword/ranseur example is likely to be faulty if they are of different types in the light of a DR argument, since their utility is derived from the fact that both were assumed to be of equal utility against any given opponent.
Actually, the setup need not assume that they're of equal utility against any given opponent.
Against humanoids, the character could use the Guisarm for the AoO/trip/improved trip routine and the greatsword when they finally close. In that situation, the greatsword is acknowledged to be of greater utility for damaging opponents up close while the guisarme is of greater utility for tripping them or damaging them at range.
Against creatures with reach, the guisarm has greater utility in round 1 (and in further rounds if you want to remain on the edge of their reach (for the ability to be more easily healed and to withdraw) but the greatsword has greater utility for simply damaging them.
Against creatures with DR, however, he could exclusively use one or the the other--(taking the AoO before dropping the guisarm if appropriate).
Against an opponent with DR/adamantium, you character will wield *only* his adamantium weapon; whilst against a DR/cold iron, he will wield *only* his cold iron weapon.
That is probably true. However, the argument is not that the greatsword/ranseur combo doesn't suffer from disadvantages in such situations. Instead, the argument is that such a combo suffers from LESS of a disadvantage in such situations than a character with a spiked chain.
First, the character has quickdraw which enables him to switch weapons without disadvantage. The spiked chain guy also has to switch weapons but loses at least an MeA (and therefore the possibility of a single full attack action) to do so.
Second, because the Greatsword/Guisarme character regularly uses both weapons, it's likely that whichever one he ends up using is significantly better than the spiked chain guy's backup. He can have 2 +4 weapons for only a little bit more than Spiked Chain Guy's single +5 weapon. There's not too much of a difference between the +4 and +5 against foes who don't care which weapons are used. There's a bigger difference between +4 special material and +2 special material.
The greatsword/ranseur example assumes that both are used and both are equally effective, which is moot in light of your reasoning. Whilst your logic is solid (i.e. multiple weapons are encouraged) its pertinency to the specific example is not.
True to some extent. Buth the need for multiple weapons was listed as Greatsword/Ranseur guy's weakness. If everyone needs multiple weapons anyway, it's not a weakness. And having Quickdraw is a strength.
Incidentally, of course, trip becomes much much more useful with the Knockdown feat (S&F) which enables a free trip attack with a weapon that deals more than 10 points of damage. It's a huge boon to tripping weapon, particularly two-handed tripper (since 10 points of damage is almost a dead cert past about levels 1-3).
I really don't see Knockdown as a very impressive feat--except for characters who could not ordinarily use their weapons to trip. (Knockdown enables a character to trip with a glaive for instance). For a character with improved trip, it would usually make sense to take the attack as a trip attack and then take the improved trip free attack instead. (That way, the damaging attack gets +4 to hit). And if the opponent is one you wouldn't usually try to trip, you probably won't take the Knockdown trip attack either--since it doesn't eliminate the possibility of being counter-tripped.