Scatter, I won't say that I have developed a fighter-type "properly". The first party I ascended had 3 fighter-types, hobbit samurai, dwarf lord and f/n. (a wiz7 import, they were complemented by a mook ranger, a fairy bishop and a lizardmen Bard, switched to a gadgeteer at lvl 3
, really fun party )
Those three had dual weapons 80, 95(with Lord Bonus) and 86 respectively at Ascension Time, so they did know a bit of dualling, but somehow the secondary attacks always seemed lacking, and when I found Excaliber my Lord stopped dualling (since no one else could use it) and it didn't look like a bad decision. True, the only penalty at that level is lowering the attack rating by one or two points, so it didn't hurt, but it didn't convince me.
Probably, if you develop chars to the full dualling is good, but if you ascend around lvl 22 and don't hit for hours on slimes I couldn't see a big difference.