Hi Nonoy Tan
,
It is extremely unlikely the hole served as a way to 'relieve' suction. A spearhead that is quite wide in relation to its thickness tends to suffer the 'suction' effect ....much more so than say a diamond profiled blade that is narrower and thicker. (the Zulu 'stabbing spear' being a classic example.)
A wider spearhead such as yours are often aimed at the neck, inner arms.... areas of the body where large arteries are near the surface of the skin. The blade would not have to penetrate too deeply to sever a major blood vessel in these areas and would quickly incapacitate an enemy. The thinner longer spearheads tend to be directed towards the head and torso to 'puncture' deeply, damaging internal organs etc.
Unfortunately, it is quite likely the hole was later drilled so that the spear could be hung on the wall.
Kind Regards David