How "effective" weapons were is very difficult to quantify since there is so little actual objective data left, particularly from early time periods. There is some date, however, from later time periods that is at least suggestive.

There is a fair amount of information published about the mass graves found at Visby, dating from the battle occurring in 1361; Bengt Thordeman's “Armour from the Battle of Wisby” is a great work on the subject. As far as I know it was the first grave find that provides sufficient data to determine what weapons the individuals perished from. A large percentage of the dead suffered wounds to the head or legs (as I recollect, about 70% of the remains show wounds to the legs), while evidence of wounds to the torso were, comparatively, almost non-existant. The predominance of wounds were caused by cutting weapons (swords and axes).

As many of the dead were interned along with the armour they were wearing, we know that many were wearing armour of the 'coats-of-plates' type. There was also a fair amount of mail in evidence (I believe about 10% of the remains were wearing coifs).

Problems with this data are that there is no evidence of the soft-tissue trauma that was suffered; if it didn't leave evidence on the bones, that evidence was lost. This may skew our interpretations of what injuries actually occurred.

Spears and pikes were considered by most warriors of their time periods to be very effective and we do have evidence showing that they could, and did, kill. "How effective" may be unquantifiable.

Both plate armour and mail will very effectively stop a spear. A couched lance can penetrate mail in a cavalry charge, but other than that they're not very good weapons for causing damage through armour. However swords aren't particularly effective either. In both cases causing serious injury tends to involves hitting unarmoured body parts or putting your opponent at an advantage (say, knocking them over) and targeting a chink in their armour.

The suggestion that a sword would be better because the soldier could aim at arms & legs begs the question. Your aim with a sword might be better - after all, you're a lot closer, but you can aim with a spear. I've seen video of HEMA re-enactors finding that aiming at the legs is a very effective tactic. Aiming at the face would be too, but they're not allowed to do that in re-enactments.

Of course, to use your sword you also have to get close to the spearman. At worst a solid spear formation has some ability to keep you away simply by pushing you. When spear formations clash, this is the 'push of pike'. Causing casualties in this push may be less important than physically pushing the enemy back, making them lose their footing, lose cohesion, and lose ground. I think I've seen some debate about what casualty rates were actually like in hoplite & pike melées, so maybe someone can weigh in with an opinion on this.