Roland RNA is actually darkness element.

The way I understand it, spellblade damage is a combined 1.35x of physical damage + 1.35x of magical damage. So a spellblade can actually do more physical damage than a warrior with the same p.attack stat(even at a reduced multiplier) and no m.atk stat because spellblades trigger in chain and damage the pincer target regardless if the pincer target falls within range or not, unlike warriors whose skills don't trigger in chain(save for some special skills). If we use Fenrir as an example, it's possible for Roland with pure physical equip to do more damage than Mizzet (both have 6x multiplier from skills) with the same equips.

The thing is, because spellblades' damage uses both physical and magical components, depending on your weapon configuration you can get even more damage equipping 2 daggers over 2 swords because the combined patk and matk of the dagger is more than the sole patk of the sword. e.x 2 Azoth daggers(SS, p116/m130 @lvl59) is better than 2 Dainsdef swords(SS, p208 @lvl59). Range can play a big factor too since swords tend to have higher patk stats but completely lack in range which means you may not be hitting all the enemies you could have been.