Not Arminian
This is certainly not evidence of an "effectual call".
Paul had several choices to be made as implied in text, and as explicit here and elsewhere.
*In Acts 9:5, 26:15, Paul asked "Who art thou, Lord?" after the light had shown and Paul blinded, Paul still did not know it was Jesus. In Acts 9:5, Jesus identified Himself. If this were irresistible grace, Jesus would not have had to state who He was because it would have been known immediately as Paul's eyes would have been opened to understand this.
*Jesus said it was HARD for Paul to kick against the bricks. He didn't say it was IMPOSSIBLE or IRRESISTIBLE.
*In 9:6, Paul TREMBLED and was ASTONISHED (frightened, terrified). Had Paul been forcefully converted, he would not have been frightened. Paul then asked "Lord, what will you have me do?". If this was evidence of an irresistible conversion, Paul would have no need to ask that question. The fact that Paul was terrified and had to ask Jesus what should he do is a clear indication that Paul's will was not overcome.
*In Acts 26:19 when Paul recounts his testimony before King Agrippa, Paul said "I was NOT DISOBEDIENT unto the heavenly vision". Obedience is a willful act.
Now Calvinists will latch on to Acts 9:15 "He is a chosen vessel unto me" and stop there. But, a chosen vessel for what? For salvation? No. To bear Christ's name before the Gentiles, kings, and the children of Israel. To say that Paul was irresistibly converted here is to add context to the Scripture that is not there. It must be presupposed into the text. By that same token, it could also be presupposed that Paul wasn't actually saved until later because he did not receive the Holy Ghost until 3 days later. Yes, Paul was called "Brother" by Ananias, but that would be because he was an Israelite, not because he was a believer (notice that Paul calls Israelites his brethren from Romans 9-11 even though it is clear that not all of the audience is saved).
It could also be argued that Paul had not yet called upon the name of the Lord even though he was told what his mission was. "And now why tarriest thou? arise, and be baptized, and wash away thy sins, calling on the name of the Lord." Acts 22:16
The clearest indication that Paul COULD HAVE resisted is, again, his testimony to King Agrippa. Paul did not say "Christ overcame my will" in any sense of the term. What Paul DID say was that he was not disobedient which is perfectly harmonious with every verse in which Paul demands obedience to the gospel. Rom 2:8, Gal 3:1, Gal 5:7, 2 Thess 1:8, Heb 5:9, 1 Peter 4:17.