That's the proper way of disabling the impact effects for the knife... *cough*

Source/Shared/BaseMelee.c

@@ -52,9 +52,9 @@ int BaseMelee_Attack( void ) {
 			sound( self, CHAN_WEAPON, sprintf( "weapons/knife_hit%d.wav", floor( ( random() * 4 ) + 1 ) ), 1, ATTN_NORM );
 		}
 		Damage_Apply( trace_ent, self, wptTable[ self.weapon ].iDamage, trace_endpos, FALSE );
-	}/* else {
+	} else {
 		Effect_Impact( IMPACT_MELEE, trace_endpos, trace_plane_normal );
-	}*/
+	}
 	
 	return TRUE;
 }

Source/Shared/Effects.c

@@ -253,8 +253,8 @@ void Effect_Impact( int iType, vector vPos, vector vNormal ) {
 #else
 	switch ( iType ) {
 		case IMPACT_MELEE:
-			pointparticles( DECAL_SHOT, vPos, vNormal, 1 );
-			pointparticles( PARTICLE_PIECES_BLACK, vPos, vNormal, 1 );
+			/*pointparticles( DECAL_SHOT, vPos, vNormal, 1 );
+			pointparticles( PARTICLE_PIECES_BLACK, vPos, vNormal, 1 );*/
 			pointsound( vPos, "weapons/knife_hitwall1.wav", 1, ATTN_STATIC );
 			break;
 		case IMPACT_EXPLOSION: